Friendships

So I’m in a friend group of 3 girls, I was friends with both of them separately before we all became friends together ... and well they hang all the time and I never get invited like ever. I think I feel some type of way because we all call eachother bestfriend but I’m never included in anything. Also when I do come around I don’t really feel welcomed. But when I distant myself they act like they care and try to figure out what’s wrong or they say I’m acting weird. I’ve never expressed that they made me feel left out because I feel like what will change? I don’t wanna force it and sound desperate to hang or ask for an invite ...I feel like if they wanted me around I would be invited... What should I do? How would you feel?