Weight lifting problems?!

I have been weight lifting for about 5 months now. I only work out because of my weightlifting class in the High School. I am currently a Freshman, we have blocked schedules so i don't weight lift every day just every other day. So on one week i work out 3 times a week. Then on the other week i work out 2 Times a week. So i have barley made any progress in getting stronger i started out benching 65 pounds and barley 3 weeks ago i maxed out on 95 with one rep. And Today i rep it twice so not much progress. I do 4 sets of 5 on one day then 4 sets of 8 on the other. In my class we do not have time to do anything else we work out for almost the whole class and then the last 15 minutes we have to run a mile but we have to do the mile in less than 10. So in my class all i do is Squat,Power Clean, and Bench. and all those sets apply so whats wrong i am having problems with with all i cant advance. One time i was doing power cleans and i just did 95 out of no where just BOOM! 4 sets of 8 then i tried it later on in the week and i couldn't even do one rep. So can some one help me please i cant seem to figure out whats wrong. I eat allot of junk food i don't get much sleep so i am always tired. Please someone help (sorry it was so long i tried to make in detail thank you)