3 missed periods and ttc

I am 24 yrs old. 5'3 165 lbs. My last period was Dec 18-22 2017.

lightly active (i work out 40 mins each day 2 miles). I take prenatal pills.

I haven't had my period since then. Im a somewhat irregular, but this is by far the longest delay of period. I'm so confused I've done multiple pregnancy pee test and so far all negative. I went to my nearest doctor last week and again negative pee pregnancy test. I came back normal in my thyroids and everything else seems to be under control. I really want to have a baby. But i dont know if i can ttc without a period. I bought clearblue ovulation kit and saturday &yesterday;(monday) afternoon i got a flashy smiley face (had sex). So if i have my calculations right I'm 60 days late (2 months). I've been with my boyfriend for 5 years now in April. Anyone else has had something similiar happen to them? did you end up being pregnant ? What should i do :( ?