I think you should try and talk to them to see what is going on and let them know how you feel, otherwise you will spend your time worrying. Don't allow others put you down, stand tall and hold your head high. Believe in yourself.
Do you have any other living relatives, aunts , uncles cousins that you are aware of , perhaps you could catch up with them? Does you foster family have familu members you can contact. Concentrate on yourself and your strengths. Whilst friends may not be the same as family at least you get to choose them!!!!! Take up new interests meet new people celebrate your life and all your talents. Good luck