Diabetes Insipidus?

For the past 3 years I have been seeing a urologist about how much I urinate, I'm 22, female, no children, I don't drink caffeine at all, and alcohol is a very rare occurrence to me. I wee over 25 times a day, and that's not even considering how many times I wake up in the night, I've been on many different tablets to none that worked, I even had a bladder stretch after being told my bladder is simple 'too small' but that didn't help either. My specialist proceeded to give me Desmopressin, and only when that helped me, I googled what it was actually for.

I have seen the greatest, and best result (only result if I'm honest) with Desmopressin, however my specialist is still on about sending me for botox. He never bothers to ask about how much fluid I'm really drinking, or how much urine I actually pass so I decided to stop my tablets and do a little experiment about how much I do.. sorry if this is TMI but here are my results:
Intake: 3 LITRES
Output: 3 LITRES 50ML
PLEASE NOTE: I am so used to restricting my fluid on Desmopressin, this was still restricted but I drank hell of a lot more, and also urinated 19 times in 8 hours. On average I was urinating 200ml each time.

I'd just like a bit of advice whether this sounds more of a bladder issue, or more like Diabetes Insipidus? I'm going to try this out again tomorrow without my tablets and be less strict with my drinking eg. If I'm thirsty I am going to drink, whereas today I put it off because that's what I'm used to on my tablets. I don't know if this is in my head or what, my urologist has been so bad with me that I don't really know what to do next. I'm going to mention this to my GP (doctor not my specialist) as I think I'm seeing the wrong people for the wrong problem, if anyone has any experience or advice to share please, please do. I'm at my wits end and I don't know what I'll do if my specialist stops me taking Desmopressin :(

xo