Can a pregnancy be mistaken for a cyst?

okay, heres the scoop: My husband and I are ttc. On April 27th I had a transvaginal ultrasound and my doctor said there was a very small cyst on one of my ovaries but there was nothing to worry about and it should go away on its own with my next period. Then on that following saturday, April 30th I got a big fat positive hpt!! And every day there after for 3 days :) Monday, May 2nd my period didnt come so I had blood work done and my hcg came back 1200. 48 hrs later I tested again and my hcg doubled to 2400. I asked my doctor if I needed to be concerned with the cyst now that im pregnant and she said no, that it could even be possible that cyst was mistaken for the beginnings of my pregnancy? Ive just never heard of such a thing and wanted to know if anyone has heard of this. If the cyst was on my ovary how could that have been the beginning of my pregnancy? But if it IS in fact just a small cyst, what do I do about it now that im pregnant? And more importantly could a cyst give off pregnancy symptoms, including hcg in my blood , and im really not pregnant at all? I never did start my period and have had absolutely no spotting. Some cramps, but ive heard thats normal in the beginning with your ligaments stretching out n all. but im confused?! I want to be happy about my pregnancy, we've had miscarriages in the past. But this doctor has me very confused with this whole cyst thing. Ive switched doctors and have another apt next monday where I hope to get more clarification but until then I dont want to go crazy :( Am I experiencing symptoms of a cyst or am I pregnant?