Really wanting a 2nd after using the Mirena but no luck yet!

Our son who is 2 1/2 was unplanned and a big surprise. After being engaged for 3 years we set a date for our wedding and 2 months after that and 2 months before the big day we found out we were expecting. We had used over the counter contraception and in the 6 years we were together we never had any problems. I guess we finally decided we may not be able to have children. I looked at it as a sign from God that we were truly meant to be married. After giving birth I used the shot for 6 months and gained weight from that I switched to the mirena. I was breastfeeding and having no periods and never had one after that. In July/08 I had the mirena removed and a period 1 1/2 weeks later, next period was on track and then the september one was 38 days from first day to first day. I have now not had one at all in October and going on 44 days w/o one. Have taken tons of pregnancy tests including early ones each cycle and they all come up neg. We are really wanting another baby but are having no luck. We haven't told anyone besides the Dr that we are trying as both families would be thrilled but would be asking everyday. They already ask when we are going to start trying and it has been getting me pretty worked up lately as we are having no luck. I keep thinking to myself that something is wrong with one of us. In particular me as my periods are totally messed up and not having much luck at all researching the mirena. Has anyone else ran into any problems with mirena? Or know of anthing that would be good info about conceiving after? I think it's hardest because we didn't try for the first one and my husband was the one who wanted to start trying again now. I keep worrying that this is going to start causing probs for me and my husband if it doesn't work soon. We try constantly and I try to keep it from being a job as it seems like sometimes. I have heard that stress, weight, uterine lining and much more can cause delay's. Please send your thoughts.