i understand and totally relate to your dilemma. i'm the same way. i feel uncomfortable showing up to groups, that are already established and the people there already know each other, and i am the "new one". Even going to vanilla groups, such as an amputee support group or a veterans group, is uncomfortable for me, the first time.
i belong to several groups on Yahoo, also, some kink related and some not. Most, if not all of these groups have a member's list, which gives some information about them such as, gender, age, email, etc. When i join these groups, i post an introduction and, usually someone writes to me at my Yahoo address and welcomes me to the group and introduces themself to me. This is one way to get to know another member of the group, on-line, first.
Also, by reading the posts, i get a feel for where people are coming from and there's usually at least one that i feel a rapport with and i will write to them privately and start a 'get acquainted' correspondence with them.
At some point, when there is an upcoming event, either i will be asked by or, i will ask, the person i have been corresponding with, if the other will be going and, if so, would we like to meet, beforehand and arrive at the event together. That way, i don't have to show up alone and i know at least one person who already knows other people and can make some introductions for me.
Of course, i have only done this with vanilla groups but, the same approach could be used with BD/SM groups, as well, i suppose.
Any way, you aren't alone, with this issue and, i wish you well in your search for a good group to join, 'offline'.
joy
Owned servant of Master David