I honestly believe 7 is a hard age nowdays. I have a seven year old too. I think with the move, starting over again it is her security for your daughter to suck on her fingers. I wouldn't do much other then explain if she does this at school, the germ factor is huge. If she does it without any thought that is hard. Maybe if you see it, gently remove her fingers from her mouth without saying a word. Maybe find some hobby she can start with her hands that she is good at, builds up her self esteem and keeps her hands busy. Like drawing, painting, piano or something like that?
My daughter only played with one little girl in Kindergarten. She was devestated if the girl went and played with anyone else. I told my daughter over and over, to find someone else to play with.
Now after a lot of talks about how she can learn different things from different kids that she should broaden her circle. Explaining how everyone is special in their own way.
Now she comes home with a different "best friend" she played with at recess. She wears her heart on her sleeve but after she and I talking a lot about what friends are, how we treat our friends and how we handle things if someone hurts her feelings I see her blossoming with just hanging out with different kids (girls and boys) each day and not making anyone exclusive or isolating herself anymore.
It took a lot of time, talking about her day every single day, I start with "who did you play with today" then we talk about what they did at recess. I don't interject too much and really listen to her.
She often tells me so and so hurt her feelings, then I explain maybe that person was having a bad day and everyone is entitled. I advise to just walk off until she cools off (my daughter can spit out the mean words if hurt) and maybe go back and explain to that person about how she feels. Sometimes it works, other times she just comes home sad about it. She has learned so much over the past few months to be careful what you say when you are angry or hurt. That has helped her tons with the kids at school.
I always tell her "you know you have no control over anyone but you, as long as you are being kind and trying, then it doesn't matter" I tell her too "you should be around friends that make you feel happy inside and help you to do the right thing".
She wants to fit in desperately and have everyone like her but she is slowly learning that sometimes it won't happen and as long as she did the right thing, it doesn't matter.
A story the other day, she came home and confessed she wasn't very nice to this little girl in her class that is heavy and kind of dresses different and is shy. I told her I appreciated her honesty, however she obviously knows that hurt someones feelings and that isn't the right thing to do. I told her I was disappointed. I told her to apologize the next day. She went right up to the girl, gave her a hug and told her how sorry she was. Now I get reports she is spending time at recess with this little girl and really enjoys her. Hearing that was so refreshing. She was not being nice because some of the other kids were not being nice to this girl. After talking to her about how to treat others no matter what anyone else does, SHE LISTENED to me! That was huge! :) Now other kids in the class are wanting this girl to play with them and I see this girl who was kind of outcasted now being included. I told my daughter how proud I was of her initiating that and didn't it feel so much better being kind then being like everyone else? She was so proud and said her heart felt so much happier doing that.
I was proud of her indeed.
It takes time, kids have to muddle through the social issues that start so early. It makes me sad. Maybe have a girl party where you can invite all the girls in her class just for fun to paint their nails and get to know them. That way I think if they can see someone from outside the class it helps make friendship easier. Or have her pick one or two friends from school she doesn't know well and go to the park one Saturday together for a picnic. I personally try to get to know all the kids in the class. That helps me a lot to know where my daughter is coming from and if it is dramatics sometimes or that there are mean kids. I haven't met one mean kid yet in her class! :)
Sorry this is so long. You are a great mom to be concerned. We can watch from the sidelines sometimes helpless and feel like it is as hard for us as it is for them. I just try to observe from afar, go visit the school at lunch every once in a while, go work in her class so I can see the interaction first hand with all the kids and get to know them for me better.
They all have very unique personalities, they change friends every other day, they are all at 7 finding their way where they fit. Good luck and God bless.