Diabetes diagnosis. Sugar came nil?

I am having frequent urination from 3 days like 10 - 14 times a day , except urination there is not other symptoms of excessive thirst hunger and weakness, can it be diabetes, i even had my hba1c and fbs checked both of which came back 5.5 and 84 respectively on 26 may, can someone develop diabetes within 3-4 weeks?although my diet was normal, although earlier it was complete opposite, i am stressed out, which test should i go for to check if it is not diabetes, no one in my family has diabetes (except 1 she 70 yrs old) today itself i had my urine routine,can it be used to rule out diabetes if my urine sugar came nil? And or should i have ogtt done, my  urine is clear , and it coming right after i drink some water within 15/30/40 mins or so, and sometimes like for today, in early morning i had two glasses of water and had to urinate 4 times within 2 hours of drinking although 2 times the quantities were quite small, color range from pale yellow to clear white/transparent.please helphhe