Helppp!!! What do i do!?

Kay

Ive always been regular , 28 day cycle. And my last period was February 15, 2018. I haven’t had a period this month and I’m 4 days late. My bf and I have been ttc for about two months now. Ive taken 3 hpt but they all come back negative. Am i testing to early? Has anyone else gone thru this. Let me know, idk if i should go ahead and make an appointment with my obgyn and see if they can do a blood test. Any advice?