Abortion failed? Or pregnant again :(

Hi there everyone, first of all can I just say its taken me this long to find a forum, support and resource that is not funded or associated with a religion and its absolute relief. Secondly all the questions i am about to ask, I plan to ask next week at the doctor, but you know how it is sitting and wondering going over things......In Mid december 2011 I had a surgical abortion, i estimated myself to be approximately 6 weeks, however during the scan at the clinic they said it was much smaller (even though that didnt even add up to my dates) BUT, they did say since it was smaller than 6 weeks, there was a chance the procedure would not work properly. However everything seemed to go as it should, very mild cramping, and a brown discharge a few days later for around 2 weeks. I had my checkup at the doc, he just asked me questions and i got the all clear. a few weeks later I had a period, granted it was more painful, heavier and a little longer than normal but i presumed that was normal. My husband and I have been using condoms, as he plans to have a vasectomy next month (would have been earlier if we could afford it) but a few days ago i started thinking, gee its been a long time since my last period and then the penny dropped that I was having all those familiar symptoms of pregnancy, so of course i tested and it was positive. I tend to believe this is a new pregnancy, considering the "period" I had. considering if it were a failed abortion i would be roughly 14 weeks now, and surely i would notice? I have 4 children already, and I am really struggling with this, because firstly if this is a new pregnancy I feel 100% stupid stupid stupid, Im not sure I could do this again, ive really only just begun to recover emotionally from the last one, and nothing has changed in our circumstances. on the other hand if there is some chance its a failed abortion, theres 100% no way I could go back and do it again. Its all a little to much fate for me. I struggled to have my other children, really struggled, miscarriages, prolonged TTC, yet these two have come so easy to easy...arrghh anyway thankyou for allowing me to put it out there and tell someone else, its so hard to walk around with this secret on my back!