I missed 3 periods. negative pregnancy tests but have most of the symptoms. im not stressing so what could be wrong?

Ovulation problem: You may have hormonal problem inhibiting ovulation. Consider seeing your doctor and getting some tests run.

A few ideas: Not having a period can be a blessing at first, but after awhile, one wants to be sure that one's ovulating. Not ovulating can mean a few things. Sometimes it's due to extremes of weight (thin/heavy). Sometimes it's due to thyroid or pituitary (you need to see a doctor to check these). Other times it's an imbalance of estrogen and progesterone. If occurs for more than 6 months, see an md.