The way that I understand it, at least with my CareFirst HMO plan is that once you have a live birth then the clock starts over. If you were trying for 4 months and had a miscarriage, the miscarriage does not count as it was not a live birth.
With my fertility treatments I was allowed 6 IUI's per live birth. It didn't matter if those treatments resulted in a miscarriage, it was not a live birth and I could continue on to the next one.
I think you would be ok to call an RE. I actually found my insurance company very easy to deal with. I was also able to find all my coverage and benefits online.