help!

My last period was feb 12-14, after a very strange 45 day cycle. My doctor put me on progesterone to regulate my cycles and push them out to 28 days because my average cycle is 25 or 26 days long. Last Friday I figured out that I would be about 5 days out from my period on my normal cycle to I tested and it came back positive! Then on Saturday I got a clear blue digital positive! My hcg Saturday was 30 and today was 84.6... so it's doubling. The doctor called and said to go back agian on Wednesday, they want another test because it is just sooo early to find out. The nurse kind of said don't hold your breathe in some other words, and has really discouraged me! She made it sound impossible that I would be pregnant and have numbers that look like that! I guess my question is, is it possible? I mean, I know they are there, and I got the positives, but, my cycles have been off this year, and this means I would've had to ovulate right after my period in order for it to happen! I guess I just need assurance! So, any of that is welcome and any stories similar too!!