cramping 6mo pp anyone?

I'm 6mo pp and have been having mild cramps on and off for the past few weeks, mostly on my left side. I usually feel them when I am breastfeeding, but do feel them other times. they seem to last longer and longer each time they occur (half hour to an hour at a time) and I have not had a pp period yet. I'm breastfeeding with an occasional bottle supplement. Baby sleeps part of the night with us and nurses on and off. I also have other pregnancy/period symptoms including nausea, irritability, very emotional, fatigue, increased appetite especially for carbs, slight weight gain/boating. I took a hpt last week and it was negative. I've been taking ovulation tests and they have also been negative. cm and cp have not been very telling. Anyone else have a similar experience? what was your outcome? thanks in advance ladies!