You are making this way to complicated. Make a plan for regular contact and ensure you meet all of your siblings regularly. Your sister sounds she has some social interaction issues - just be kind to her.

Remember you can not force yourself into a relationship with friends or family. You have to accept what they give you. Personally I would be very happy that out of 10 siblings - 9 seems to like you a lot. Believe me - in any families you will not have that.

I think you need to start what is important - and that is yourself. You are going to have a life apart from your family and you need to give yourself time to deal with these things. You said you have depression. Depression is not solved by focusing on outer issues, but inner issues.

Finally, you adoptive parents. I understand they might not have been dealing correctly with your situation, but it sounded like they cared. I understand that you would like to have a relationship with your bio parents - still to be frank - your adoptive parents were the ones that wanted to have you as their daughter not your bio parents - and as such they did their best. You need to decide how you are going to have them in your life.

These things are complicated - and even more so with someone in your position. Just remember - you will soon have your own family - ensure that you have a clarity on how you want to deal with your extended family - but make yourself the best person you can be for your future husband and kids. They will be the one you need to focus on.