I am having tender breasts. i am on depo-provera and had sex back in early may. i took plan b and 3 pregnancy tests all negative (may-july). could i be preg?

Unusual: Would be unlikely at this point to have neg tests if pregnant. See your doc for a blood pregnancy test or for other reasons.

Common side effect: Tender breasts are actually a fairly common side effect of Depo-Provera injections. I would think that with the timely ingestion of the Plan B within 72 hours of the unprotected sex and 3 negative pregnancy tests you can be fairly sure you're not pregnant.