Do light periods affect fertility?

Hi, we've been ttc for 6 months with no luck, and as far as I can tell we are doing everything right! The only thing is my periods are really light. I normally have about 3 days when I only use one pad and then 3 days of spotting. When I first started my periods at age 11 they were really heavy but as I've got older (I'm now 31) and been on and off various pills they just get lighter. I feel awful with back and abdo pain the first day or so though, and usually have pmt for about 2 weeks before! Do you think there's something wrong with the me that's affecting my periods and fertility?