My hcg levels have been in the 200-300 range. I also have a mass that is about 3cm?

Has anyone ever had low hcg levels & a mass that was about 3cm & still have a healthy pregnancy? I still feel pregnant & Ive been bleeding off and on. But no pains at all what so ever. My levels went frm 170 184 to 244 to 236 to 234....?!? My ultrasounds hav been weird as well Ive had them at one point in time back to back & nothing was seen, my third ultrasound the seem the mass my forth one they seen a gestational sac but the mass was still there & my last blood count was 234..what does ths mean?! I was ask to get the shot to abort the baby but I'm not sure..I've read alot & did alot of research...I'm jus so confuse & curious y my hcg level haven't been Goin up like they r excepted...do I hav hope?! Pls someone Give some advice..