Reasons for my sudden adult acne? Maybe PCOS?

It's good that you're going to see your ob/gyn - ask him/her to run a hormone panel on you. Explain about your sudden onset of acne. My guess is that your hormones are still out of whack from giving birth... also if you fed/are feeding, it takes even longer for things to even out. Your doctor can figure out if it's PCOS or something else, though.