Miscarried 4 months ago and still no period?

I miscarried last year December 25, 2010 and I bleed for about 2 weeks. It is now four months later and I still haven't had a period. I miscarried at home, but took everything in to the ER and they used a l probe ultrasound camera (whatever it is called) on me and told me that I had a complete miscarriage and nothing was left over and even monitored my hcg level for the next week until it was at 5 or below. I keep reading that 3 months is the longest a period should take to start back up. I really want to start trying again, but it is sort of hard when I'm not getting a period, Also, before I got pregnant I had irregular periods that came every 3 months and even so, It's been over 3 months and still nada. I'm asking this question because I'm thinking of calling the doctor, but I want ti make sure that it's necessary.