Reoccurring UTIs

I have always drank a liter of water everyday including my coffee in the morning and a glass of water with my pills in the evening. I did this for a year and a half without getting a UTI which is the longest I've ever gone without having one. Now it seems I'm just getting one after the next and sometimes when I am on an antibiotic. My urologist nurse told me that I should be drinking a gallon of water a day. I have tried to step up my drinking by adding 1 extra glass of water in the evening and one extra glass of water in the morning. Now I have started another antibiotic after having my urine cultured and I believe I just got another UTI right before I started this antibiotic or right after. Sometimes when I drink a lot of fluids it comes out throughout the day but sometimes my leg bag won't fill up for hours and then it'll all come out at night. There are days like that when I noticed a start of chills and headaches which is my tell tale signs for a UTI. They have not dissipated since starting this antibiotic. Should I continue on with this antibiotic or should I get it cultured just to make sure I don't have another bug that needs to be treated with a different antibiotic? Also, what should I be drinking every hour of everyday to ensure continuous flow of fluids?

Reoccurring UTIs