Hey Kitz. I just found out that i am pregnant with my first bub as well. I had a doctors appt yesterday but couldn't attend so I have resceduled the doctors appointment this afternoon to find out dates but i have had 3 positive HPT's now. I totally understand what you feel, i don't really "feel" pregnant at all, the only signs i have had are normal signs i would get if AF was coming. I still have a little bit of cramping which i am very worried about but fingers crossed all goes well.
If you are feeling unsure then do another HPT, there is no harm in doing that at all. I hope you have a happy and healthy pregnancy and your scan turns out very well for you. Good Luck