SUGGESTION?!?

So my OB had me on Birth Control for 3 months to try and regulate my cycle. As well as weight loss meds and migraine meds. I have successfully lost 37lbs. I have continued on my meds. I was taken off of my BC after those 3 months. Since then I have had one period and I am now 15 days late for my period. I have taken 3 pregnancy test every week for last 3 weeks. All negative. I have been feeling bad. Sick on my stomach, tired, no energy. Does anyone have any suggestions? I go back to my OB on the 15th of August. I do have PCOS also ENDOMETRIOSIS. Dr said loosing weight will help in regulating my period. So many questions?!?