What Causes Burning Sensation During Urination With History Of Having Cystitis?

About two weeks ago I noticed that it was burning a little when i was peeing, i had a cystitis flare up when i was 16, i am now 27, so i knew the signs, so I went to Boots and brought on the shelf medication to treat the same , this seemed to clear it up, but then the following week it happened again, so i done the same thing as was not able to get time off work to see my GP. It does not burn when I pee anymore but i am finding i am not passing urine as much and sonmetimes my urine is darker than normal, but not sure whether i am drinking enough fluid. I dont know what to do and an worried as i am a type 1 diabetic