intermittent symptoms - slight urge to pee / occasional fullness

I'm 34, male and for more than 2 months now I've been experiencing some strange, vague symptoms which are actually hard to describe as there is no pain or anything severe physically.

It's like a slight sensation of fullness with a very slight urge to pee which is more prominent at night and disturbs my sleep. I wake up around 3/4 am on and off for these 2 months with that slight sensation. Sometimes it makes me want to pee but most of the time I don't need to go so I don't, so it's not really that severe. However, I'll have days where I'll be fine and infact the last two weeks I've been mostly fine, felt like myself. And so I thought, ok that's it then, thank God.
However the last few days, it's back again. The strange sort of gut mild discomfort remains from time to time. Occasionally I'll end up having an urge to pee and some days I have voided alot more than other days when I've felt more myself.
I've never had pain or burning or straining when peeing and there's no pain whatsoever anywhere else. But it's almost like there's something there, I just can't put my finger on it even if it's not consistent. I notice I feel "on edge" during one of these moments. So I don't know if it's anxiety related.

Been to the doctor 3 times, I've had urianalysis samples done 4 times, all normal, tested my blood glucose level several times using home testing kits before/after meals and that's normal too. I thought about prostate issues but doctor said it's highly unlikely at my age.

I started on mirtazapine 15mg around mid October and initially I only had some drowsiness in the morning as a side effect. I then stopped it altogether about 2 weeks ago now.

I realise none of you can diagnose on here but from what you're reading does this relate at all? Does this sound like some kind of bladder issue/sensitivity?

Hi Bay Area guy and thanks for the reply.
I don't think there's been much difference to my routine or drinking habits at all in the past 2 months. I do consumer large amounts of tea but I have been doing this for many years now and never noticed a difference in my urination habits.

There are days when I’ll drink say around 1l in the afternoon and won’t even need to go pee for almost the whole day and if I do then I’ll only void a small amount but then there are days where I could drink the same amount and I’ll void a fairly large amount, near the 1l that I had drunk. What’s the reason for this variation? Is this just normal and dependent on the individual?

During the times when I’m not voiding much, my urine is rather concentrated so a lot more yellow than the times when I void a fair amount, where it’s diluted and looking very clear. I have no pain, no straining, burning when urinating but just an occasional slight urge to urinate as I mentioned.