Easy 10pts do you think i could be pregnant ???

ok i been taking clomid 50- 100 and now im weeks late on my period but when i had last ultrasound with RE ( firtility specialist ) they where checking to see if my follicles matured and they didnt but they DIDNT i havent been late on my period in a while why am i now 3 wks late whats going on ?? i tested after 2nd day of missed period and it was (-) but i did use a $1 test but any way do u think its possible for me to be pregnant or did the clomid just mess me up ???