You have missed you period for last two months. However as your pregnancy
test several times has come negative it looks like you are not pregnant.
It would be best if you could get an ultrasound
pelvis to rule out pregnancy still and also find out if there is any other problem in your reproductive tract.
Have you had problems with your period before?
You need to get some blood tests like LH, FSH, LH:FSH ratio, (reproductive hormones)
TSH, T3, T4 (thyroid
fasting and post lunch. Take the reports and see a gynecologist who can tell you the exact problem and what should be done next. It could be that your hormones are not balanced and so you are having all these symptoms. Once the exact cause is found out you can take some pills to regularise your hormones and periods.
Till then do not worry and take a healthy diet. Include mild exercises in your routine like walking for 30 -45 mins.