How am I not losing weight?

I don't eat and haven't in 2 weeks and the last time I did it was 0 calorie pickles, I drink a lot of water and monster energy (4 - 6 cans a day) and walk at least 4 times a week for 45+ minutes and do 50 jumping jacks a day. I'm on my period too, would that make the numbers on the scale stay the same? I usually lose about .5 to a pound a day but it's been really slow the past few days. I'm a 17 year old female if that helps. I'm 135 pounds and my goal is 100. I just went walking for an hour and came back and it said I went up to 136. Thanks for any help and please don't tell me to eat.