I Do Not Have Regular Periods, However, When My Period

I do not have regular periods, however, when my period occurs it is usually heavy and last about 5 to 6 days. I just started my period. The first since March of 2014. I'm concerned because it's brownish red and very very light. I usually go through 7 to 8 pads a day. I've only had to change my pad once a day and there is barely any blood when I do. I don't think I'm pregnant because I haven't had inner course since the last week of July. But I've had breast tenderness for the last 3 weeks and they feel heavier which isn't normal for me. My cramps are a little more frequent and I've had dizziness and nasau. I was just wondering if I should be concerned?