Femera 2.5 or 5 mg ?

I have done 2 cycles of femera 2.5 mg . First round I took on 5-9 and then second round 3-7 . I ovulated around cd 13 or 14 and but I still had bfn at the end . I don’t know if I should increase the dose .

HELP!!!!

What days would you recommend ?