What Causes Delay In Periods After Normal Menstruation After Childbirth?

I've got my period twice since I gave birth to my son in Feb, the first time it came on the 13th of June, the second time it came on 20th of July. This month I didn't get my period...Is it possible to get your period once a month and then miss it because of childbirth and how it takes time for your body to get regular again? My hubby and I have been trying to conceive, so I'm trying to figure out if I may be pregnant... I'm not breastfeeding either, I did a pregnancy test which came back neg a week ago. I had a few dizzy spells, and a metallic taste in mouth and also excess hunger in the mornings... There was a time last month that I thought I was PMSing, I was moody, and usually that meant I would get my period, but it never came. And then later in the month I had a milky thick discharge which turned clear and watery, could it be possible that I ovulated late in my cycle? which means I would have to wait 2 weeks from that date to do a pregnancy test? What should be my next plan of action?