I started my period two weeks after the last one ended, i have a 32 day cycle. no std, or sti, or hormonal imbalance, anything. why am i bleeding?

Other ideas: Other indications for abnormal bleeding in someone your age would be weight (thin/heavy), thyroid, vonWillebrand. Those are some options. The most common, however, is going to be hormonal, and since there's no 'real way' to check hormone levels at 18, I'm wondering how you diagnosed that hormones weren't the cause? What about considering birth control pills if all else checks out normal?