My blood group is o+, my boyfriends b+.If there is any problem in future we have baby? And what is more possibility have boy or girl?

No problem. You have o + o from your parents. + is dominant and - is recessive, so you could be ++ or +-. B is dominant and o is recessive. Your boyfriend could be b + b or b + o from his parents. The possibilities for your baby are b+b=b, o+o=o, or b+o=b and ++, +-, or --; so your baby will either be b+ or b- or o+ or o- from the two of you. Boy or girl is still 50/50.
No problem. Both of you are rh positive which indicates that your child will also be rh positive. The issue of sensitivity arises when the baby is positive and the mother is negative. This will not happen with you. The blood type has no effect on the sex of a pregnancy so you have the usual chances which is 108 boys for every 100 girls.