I was thinking about your saying how the group photos looked:
Remember, they have probably already been together to form that bond that showed up in the photo but being a meetup group there are always NEW people coming into the group & each of those came into the group at one time when they were NEW & didn't have the connection to the others created yet.

I started going to a ballroom dance class that had been started probably a year before I got involved. Everyone knew each other & the connection they had was wonderful to observe. I was the new kid on the block, the outsider wanting to come in.

I enjoyed the group for about a year before things came up that made it impossible for me to go until last summer when I was able to start going again. Many new people had joined in the time I was away & their new bonds had been created. I have been going this whole time with a few exceptions but it's an amazing supportive group & we all cheer each other on when we get the new steps & practice them together. I have grown so close to this group that even though our instructor started a group in my own town, I can't imagine leaving the wonderful dynamics that I have grown to have with the group in the neighboring town & truly miss the nights when I can't make it to class.

Though I started also going to the one local to my town because all my friends around my town are going to that because I was the one that talked them into hiring our dance instructor to teach here & I enjoy the group of people that I already know.

The thing is that bonds are made the longer you meet with a group of people & it takes time for those bonds to grow but they are amazing after about 6 months of getting to know each other & doing things together.

Be patient with yourself & just find something that you have an interest in because the others with that interest will interact & the bond forms naturally without the work that it takes otherwise.