Am I pregnant? test this morning was negative.

I have been having 28 day cycles like clock-work since February or March, since my doctor put me on bio-identical progesterone tabs. I take 200 mg/day; day's 14-28 of my cycle. My period always begins on the 28th. I then count the 28th day, as day 1.

I recently became sexually active (I'm 23), as in, a few cycles ago. Last cycle, my period came 1 day late; on day 29 of my cycle. It lasted the normal length (5-6 days). On Day 5 and 6, I had sex. Paranoid that I could be pregnant, I waited a couple weeks, and then took a home pregnancy test. Negative. I then took another one 6 days before what I thought would be the start of my next period (day 2 and it also was negative. A couple days before day 28 (must have been somewhere between days 25-27) I had sex again. On day 28, my period did not come. On day 29, my period did not come. On day 30 (today), my period did not come, and shows no signs of coming. I took a pregnancy test this morning, but it was negative.

On day's 19 and 20 of my cycle (or was it 18 and 19) I had a dull, constant pain on my left side. At the time, I thought it was my ovary, but now, I'm not sure.

Other than that, I've noticed that I can't seem to orgasm lately when having sex; I've always had a hard time, but now, it seems impossible. I almost get there, and then it STOPS. So frustrating. I've also been tired but that is sorta normal for me..

Could I be pregnant?