I'd encourage you to get back in contact with your friends, just because things are different, doesn't mean you can't still have meaningful interactions with them. Your energy doesn't have to match to be friends with a person, of course you're two different people. One of my best friends (who I've known for 15 years now) are opposites in a lot of things, we are still incredibly close though. Try not to put unnecessary barriers in your way. Build friendships with them, if it doesn't work, then it doesn't work, no skin off your nose.
Regarding your boyfriend's sister, she could just not gel with you as sometimes siblings don't like their sibling's partner, doesn't necessarily mean anything. Just be kind and courteous.