Could I be pregnant? :-)?

I am using Gonal-F and Ovidrel injections to develop follicles and ovulate. I did the Ovidrel injection on Thursday night (1 week ago from tonight). I feel very bloated, more tired than usual, and I felt some light cramping and tenderness in my lower abdomen (no bleeding) today. I know it's too early to take an HPT, but when would be the earliest I could possibly get a positive result? Also, is there a way to tell if these are pre-period symptoms or pregnancy symptoms?