Tina I had the exact same problem when I got my BFP - I couldn't tell if it was for real, of if it was as a result of the trigger!

What was your dose of pregnyl? I used this as a guide:

Q: Can I use an HPT if I had an hCG injection (such as Profasi, Pregnyl or Novarel)?

A: You can, but you should wait 7-14 days after your last injection before the shot is out of your system. If you test too soon, you might get a false positive. Wait 14 days after a 10,000 IU injection, 10 days after a 5,000 IU injection, or 7 days after a 2,500 IU injection.

ETA: The only sure-fire way of telling is to get a BT 3 days apart - if your HCG levels go up, you're pregnant!!