confused!!

Katie

just looking for some advice or anyone with similar issue..I had a baby in December and periods returned after 6 weeks since then they have been regular 32/35 days apart (normal for me before baby) Junes however was after 40 days and now we are in August and I havnt had one on day 47 now. I've taken a pregnancy test this week and was negative but I have had cramps sore breasts and nausea for 2weeks now. has this happened to anyone? should I test again? just worried after it being regular and now something has changed that something might not be right. not stressed or anything like that so don't know why it would be so late and get a negative over a week after af should have been due