TTC- what is this feeling?

So my husband and I have been TTC for 3 months now. Every month AF has came. My last period was 3/5-3/9. My fertile days were the week of the 18th. I take my temperature every morning. Based on my temperature I ovulated between 3/17-3/18. We had sex early morning (like 2 am) on 3/17. Saturday 3/19 I started feeling cramps (like gas pains, but I'm not gassy) in my lower abdomen and they are on and off throughout the day. Now today 3/21 they are still there. Could this mean I'm pregnant? When should I take a test? I'm too anxious to wait to miss AF. My next period is supposed to come between 3/28-4/2.