Why do I feel a constant pressure to pee?

Hi doctor,

I am a 21 years old. I have been suffering from frequent urination. I have never experienced bladder problems before. However, I do suffer from severe period pains. Is there any relation between the two? From the last few months, I have to pee very frequently. I was working a lot when this all started, so it was not too bad, as I was constantly busy and I had no time to think about it. I also feel as though it was not as bad as it is now. I am now unemployed, so I have a lot more spare time, so I do not know if this is a psychological thing, which is making me feel like it is worse.I constantly feel the pressure in my bladder to pee, and I feel it significantly when lying down. If I take a nap at any point or if I lay down, the pressure on my bladder is insane. Even if I go to the toilet, I feel the need to go again straight after. I have been to my doctor recently, and I explained my symptoms. He prescribed Trimethoprim, which I have been taking for three days now. I feel uneasy, as the doctor said this antibiotic normally works in two days. I am going to remain positive and do my full seven-day course. I have also given a sample of my urine to be tested, and I have also booked a blood test for tomorrow morning. I have been fasting recently, so the dizziness and dehydration are expected.

I have been holding back on drinking water, as I fear this will make it worse. So, I drink two glasses of water maximum a day. I have read a few things online and realized that I have been doing the wrong things as drinking a lot of water will help wash the bacteria out. As of today, I am going to drink two liters of water a day and incorporate that into my lifestyle. What is it that I am suffering from? I have no pain whatsoever and no burning sensations. I do not have blood or cloudy or smelly pee. Will this ever go away? What can I do? I would really appreciate any help or professional advice. This is really starting to take its toll on my life, and I am beginning to feel really restless and unhappy. Thank you so much.