Awkward situations

Em

Long story short bf and I had sex. (A month ago ) I haven’t got my period. I took a pregnancy test and it came out negative. I am not on birth control. The other day I pulled my back and I have a bunch of zits on my face. ( I also way over 300lbs ) this is just stressing me out. what’s any ideas on what’s going on ? Should I tell my boyfriend? can someone just skip a period?