J.S.
This is really something that you need to discuss with your OB. She's likely going to tell you that the changes are due to your age and not pregnancy. A change like this isn't a sign that you're not living a healthy lifestyle. It's just a natural progression. In the event that it's not "for you specifically" you still need to mention this change to your OB.
Assuming that you're perfectly healthy and the cramps and PMS are just how your cycles are now, I would be more likely at your age to go with an IUD than the pill right now, to be honest. The pill can really mess with your hormones and cause some horrible weight gain issues, blood issues, and other problems and they take MONTHS to clear out of your body. You need to wait until your body adjusts itself after going off of the pill which can take 3 months or a lot longer before you have consistent cycles again.
With an IUD you can make an appointment to have it removed and start trying to conceive immediately.