Hi Claer. Side note: I did not read all of the posts but think the topic very interesting and something that comes up often in groups.
I think that for some people, choosing to have or not have children does have to do with their spirituality. For others, it has nothing to do with spirituality. It is not -inherently- part of Druid spirituality. However, having children is part of the natural way of things and some people take this very seriously, overly seriously, to the point of judging those who do not have children or wondering what could be "wrong" with them. For most parents, parenthood is a defining part of who they are. Becoming a parent changes your life and your self-definition drastically, as well as changing your place in the society, the family group, and oftentimes the spiritual group. It may be more accurate to say that the people in the gathering you attended were more caught up in their self-definitions as parents than in your definition as a non-parent. Because they had come to self-define so greatly with their role as parents, it was perhaps hard for them to remember their own roles as non-parents before they had children. It is likely a cultural expectation in your area, particularly in the pagan community, that women will have children. With a lot of focus on the threefold goddess, the role of the Mother, etc, I can see how that could be considered a normal part of a pagan community.
I have always thought it really odd that where I live mothers and parents are actually ostracized a bit and children are not expected to be included in rituals, celebrations, spirituality unless it is specifically a "kids" event. It is as though I have to have separate groups for me and my family. I understand that for certain things, certain types of rituals or practices, but many groups around here expect you to be childless or so separated from your children that you WILL leave them somewhere to do your pagan things. It is an expectation. Some groups will even exclude you and tell you to stop practicing as soon as they learn you are pregnant, as if your status as a pregnant woman makes you less human and less spiritual and less capable of doing magic or spiritual work. It is not as if you gain some much-sought-after status in the group and elevate yourself to the status of "Mother." So here the problem is kind of the opposite. People will look down on you for being a mother, especially if your children are young and you are hoping to continue doing pagan things with them or around their schedule (ie. meetings that start before 8:00 PM so you can get a babysitter).
It is sad that you were made to feel strange or less pagan. I don't think you are less pagan at all. In some traditional societies, the childless women were considered more able to explore certain spiritual paths that mothers simply couldn't easily explore until they reached menopause. Childless women could also take on various "men's" roles or spiritual positions that a mother could not. In a traditional society, a married woman was usually a mother unless she or her husband was infertile. Sometimes a woman who was thus marked as "other" was considered to have certain spiritual gifts that others did not have. I don't see why a woman who chooses to remain without children should be looked at as "inferior" to mothers.
Other aspects of the Mother in paganism have absolutely nothing to do with children. People can be mothers as nurturers, as creators, as artists, as sustainers, as farmers, as mentors, as guides, as teachers, etc. Being a mother, in the pagan sense, does not mean you have to have children born of your womb. Some groups will emphasize that, and might even ostracize women who are childless for whatever reason and may have classic problems tolerating homosexuals. This is not a pan-pagan or druid philosophy.
I think it is wrong to question a woman (or man) on their reasons for being childless. Who wants to explain themselves, as if it is something deviant that needs defending? If the person really wants children but has a medical reason for not having any, that is a likely to be a touchy subject that they do not want to repeatedly explain to every parent they want to befriend. If the person has chosen not to have children without having a medical reason, what does it matter? Asking someone if they have children or if they plan to have children is really not confrontory, mind you, and is different than badgering someone about the reasons for their choices. It might seem like questioning, if everyone you meet is asking you over and over again if you have children, but if they leave it at that, then it's perfectly OK in my book. If they all go on to ask why and act like you're an anomaly, as it sounds like the people at your gathering did, that is a bit odd.
It is quite normal to feel hurt by the pestering and judgments of others, especially when you are trying to befriend people and have a good time, only to leave stressed and overwhelmed in a bad way. It might be a good time to bump up your responses to such inquisitions. Being overly rude might not help you make many friends, but if people are going to push their noses into your business and be negative about it, you probably don't want to be looking to them as your good friends anyhow. Perhaps you can "jump the gun" and start conversations with obvious mothers with something about how you can't see yourself ever having children. I have a great friend who has no children and really doesn't foresee any in her near future, and she quite often brings up her ideas about parenting and such as a defense mechanism against people questioning her. If you bring it up first, you own the playing field. If people then want to challenge you, they are obviously confronting you, which is less likely to happen when you have already established your opinions as opposite to theirs. It's just rude to challenge people like that. Whereas, if someone comes to you and says, "do you have children?" they have the opening advantage and can continue the conversation with questions about why you don't and your own choices and all of that, feeling that they have the right to do so under the guise of "getting to know you" or "keeping the conversation going." I have often seen people come in and say, "I like other people's children but really can't fathom having my own!" and everyone just smiles and goes on to another conversation, rarely questioning the person for the reasons behind their statement.
Well, gotta go feed the kiddos. ^_^
Good luck with groups in the future. I hope things get easier in your dealings with pagans and parents and pagan parents.