Pregnancy test after HCG shot?

Stephanie
I received a trigger shot on Wednesday last week.  Since that's a HCG shot, will I be able to use home pregnancy tests?  Or will the doc have to do a blood test maybe?  Or something else?
I took a HPT yesterday just to see and it was positive.  I know it's WAYYYY too early for that to be legit, so I'm guessing it's the trigger shot I'm seeing.  Any advice?
On a side note, after 10 months of trying that positive was amazing to me, even if it was false. :)