A normal healthy couple should result in conception if they are engaged in regular sexual activity for past one year.
Since it is already more than 1 year,you should consult a fertility specialist to get properly examined and investigated thoroughly.
It is important that both of you get examined and investigated.
Same blood group
is not the cause for infertility
Chances of conception are best if sex is done on days 5 days prior to ovulation and on the day of ovulation.
Ovulation day falls on 14 days prior to period in a cycle of 28 days.