Period Post Partum

I'm four months PP, and I don't think I've had a legit period. I've had light cramping a couple times before a three day bleeding session, and I've spotted several different times. Sometimes it's 3 days of bleeding, 4 days no bleeding then the next week it's the same, other times it's 2 weeks before I bleed again. I started the pill at 6 weeks, and pumped for 3 months, never breastfed, just pumped. Is this normal? When will my periods even out?