Screwed up cycle

So in April I had a period April 4-8 then again (super heavy) April 21-25. The glow calendar showed me to start May 11. I haven't started. I have 2 children already and can't remember being this "off" with cycles and pregnancies. My hormones make me "feel" pregnant but I took a test first thing this morning and it was negative...any insight why I would have 2 periods in April and be late now?