20 hour fast

I started the fasting idea of coffee and cream for breakfast and slowly increased my fasting window from 16 hours to 20 hours. I have been staying eating btw 4:30 and 8:30 for over a month. I have protein at 4:30 1/4 cup almond butter with chia seeds and then dinner from 7:30 till 8:30 eating a big salad with meat ( like 4 oz )1/2 cup cottage cheese, half an avocado, nuts and a cup of cooked veggies. Then for dessert 1/2 cup oatmeal with berries and milk. My weight has been stable and I feel good. I had a planned joy eat last weekend for graduation. Weight went up 5 lbs overnight but off again after 2 days of the normal routine. Since then my weight has been jumping around and I am wondering if I should open up my fasting window to bring it back to stability. Today I was up another 7 lbs but the only thing I did was a second bowl of oatmeal and 2 cookies as we had another graduation party. These huge fluctuations are baffling me. My other thought is possible water retention from allergies? I usually weigh 122. I am 5’4”. I walk an hour a day and that is consistent. Feeling confused and afraid my body is acting this way. Will continue to be patient and observe with curiosity but any input appreciated. Thank you Brooke!