Aspirin

Hi ladies! I am going to the doctor tomorrow and plan on discussing this wth her, but I'd also like to know your experiences. I suffered two early miscarriages in June and July of 2015. After the second my doctor offered me a recurrent miscarriage screening. The only things that came back abnormal was ANA positive (I've seen a specialist and I have no autoimmune problems) and MTHFR heterozygous (the kind the effects the way the body processes folic acid). I was told to start taking baby aspirin as a precaution when I became pregnant again. My doctor told me I could stop after 12 weeks, but now I am 17 weeks and have yet to stop. My worry is that once I stop I will miscarry. I trust my doctor and her judgement, but I just can't seem to let go of that fear. Has anyone been in a similar situation and what did you do?