I need help!!

Okay so I was diagnosed with PCOS at the beginning of this month nd I've been TTC for about 4 months now. My doc told me if I lose weight it should help me get pregnant. I told him I've been goin to the gym for almost a year. I used to weigh 227 nd at the beginning of the month i weighed 204. I lost about 20 or 25lbs already thru that course, I coulda lost more but I fell off coarse alot but I always got back on track so anyways! He prescribed me Phentermine(help with weight lost) nd Metformin. So I was suppose to start my period last week. I felt like I was pmsing, even had a lil spotting one day but it never came. So I took a pregnancy test I believe Wednesday nd Thursday nd both were negative. Today's almost the end of the month nd i STILL haven't gotten my period. I took another just a couple minutes ago nd it came out negative too. So my question is, does any of the medication I'm taking now affect with your periods?? I mean the only time I had irregular periods was when I had my IUC in, which is the Paraguard thats made outta copper. I took it out in late May. Nd ever since then my periods have been normal, up until this month when I started takin meds. So pleeeeeease if any of y'all kno anything I would very much appreciate your comments. Thanks!