UTI or BPH. 25, i am getting problems!

Hello there, i am male 25, i am getting problems regarding urination, and its getting worse. I was not aware about this until now. Problem is i am having frequent urination, in day as well as in nights and still feel like my bladder is not empty completely. I dont have any discomfort or regular burning sensation during urination. Its rare when i drink 2 or 3 litres of water, but mostly i drink above 5 litres of water, and still feel thirst and quench. I also have problem of dribbling and the flow of urine is very low. Also i feel like it causes me erectile dysfunction and low libido. I did some research on google about it.. and i found two reasons for it UTI and Prostate enlargement but i dont have other symptoms like fever, or discomfort like burning sensation, i just have symptoms mentioned above. And its getting worse day by day. What medical tests should i do or what should i do to diagnose what problem do i have ? Uti or prostate enlargement. Please guide me properly . Thank you.