Could it be scaring in my uterus?

I found out my second daughter had trisomy 18 at my 20wk appt. at 23 week we discovered she didnt have a heart beat anymore and i went into labor, but wasnt progressing, so my doctor helped progress to deliver her natural. However, the placenta wasnt ready to deliver so i also had to have an D & C done. I have since been trying to conceive and it is going on a year unsuccessfully and i have also tried taking clomid and still nothing. I feel as if my periods now are more cloty then they were before but i dont know if its because i pay attention to them more. They for the most part are pretty normal anywhere from 28-31 days and lasting 5-7 days, but since having my daughter they have been VERY heavy.  and on a side note my first daughter was conceived through IUI after 18months of trying, second daughter conceived naturally after 5 months of trying (but ended in miscarriage) any thoughts or help?!?!?!?!!!!