ick!
as far as ntnp vs preventing right now, I'd give it a month or 2 to see if you really ARE going to start cycling normally or if this is just a fluke. If you are cycling I'd probably put forth effort to prevent for 3-6 months unless you are ok with getting pg immediately. that way you aren't putting it off long if it does take some time like before, but you won't have a heart attack when you end up pg with a 4 month old either!