Oh CAJ, sweetheart......no wonder you've been miserable....listen first thing is that there is LOADS of great advice here from people so i won't repeat what they said but i will say that it is NOT your fault as you've done everything and continue to do everything you can to bring your brother and your foster mum closer to you.
It is their choice and a stubborn one, may i say, and as said, their loss as they would get to know a really lovely, sincere, genuine person in you that just wants to be loved.
And you are by your very wonderful sounding, and may i say, very lucky boyfriend, to have you as his girlfriend!!
I do hope you stay together forever and it would be nice if you can get to meet new friends and make some real close attachments to help you feel that you are so special.
You are special,Caj and dont let anyone ever tell you otherwise.
( oooh,if i was'nt married and you did'nt have a lovely b/f!!!)
Best of luck and know you've done all you can ........if you decide to stop contacting them you'll know you've done just that!
Lots Of Love to you, sweetheart....always
xxx
Ian xxx