Missed Period

My last period was Feb 23-27. I had sex Mar 6th and haven't had sex since. In March I was suppose to get my period Mar 22nd and nothing. I had cramping alittle spotting and still no period. It's now Apr 4th I have taken two pt and both said negative. Right now nothing in my life is stressing me out. I drink plenty of water and exercise daily. I have been sleeping a lot and there has been a few times I slept all day. Could I be pregnant? Should I keep taking a pregnancy test or go to a doctor to find out for sure?