period coming often!

sorry this is so long. I had a baby in Sept '16, so im almost 11 months pp. My periods are all over the place! only once, since baby was born, have I went close to waiting through a normal cycle. went 26 days. its gettong ridiculous, im mostly now only having 5-8 days in between periods. they are lasting 5-11 days. has anyone had issues like this? I feel so worn out all the time now! I had surgery for endometriosis about 7 years ago and wondering if thts the problem, have also heard of something called PCOS too, sounds like tht cn b a symtom. I'll be going to doc in a week or so, hope for answers soon