Confused??

My period was due Dec 10th-16th during that week I was spotting on/off. Dark brown discharge(light) dark red to bright red with tiny clots (little bit heavy but not too much) pink to dark brown again. Back on 26th I took plan b while I was already/during ovulation..during that time that my period was due I had no PMS symptoms whatsoever. It’s been almost 4weeks since then and now I’m having symptoms like my period is about to come..I did take a HPT awhile back and it was negative but I didn’t take it in the morning like it says too so...I’ve been having symptoms(some that I wouldn’t get with PMS). I’m overweight and it says there’s no effect of the pill for me..I’m pretty sure the side effects should be gone by now. Help!! I’m confused