Why am I peeing so much?

Maybe try not to drink 2hrs before your session. Also male squirting. It sounds like part of the fluid your peeing, is precumish. Which is what one sprays during squirt orgasms. 2hrs should be sufficient to clear your bladder. 

Hello

Really, as @tbob said, avoid drinking too much fluids before your session. Sometimes it happens to me too. observe the frequency for a while. I don't think there's much to worry about.

Possibly the need to urinate is more evident due to the stimulation of regions close to the bladder, the duration of the session (the time that does not seem to pass during pleasure) and the greater concentration on body sensations.

Are you sure it is only when you do a session?  Just due to family experience, my first thought is potential diabetes.  Depending on your insurance, you may be able to buy a cheap glucose meter and keep an eye on your blood sugar levels for a week or so cheaper than going to the doctor to get checked out. If the numbers are high, get in to see the doc. 

@tigerwarrior,

The bladder issues can be a bit tricky from my own experience.  Hydration is important for overall health, and over or under hydration can both cause issues.  Also, a restriction in the system can cause your bladder to not empty when peeing.  In this case you will have to pee again somewhat soon after you peed, if that makes sense.  This could be the beginning of what is called OAB (over active bladder) and that can take time to "rewire", as they say.  It also may require some medication short term, so be careful of the medication's side effects.  In my experience, I was diagnosed with BPH by my GP physician, but we did not know how pronouced it was until a urologist did a full work up of the system (bladder through exit of the urin) by measuring the pee amount, force of stream, look inside the bladder with a camera, and a rectal ultrasound to measure the prostate size.

I am not saying this is your issue, but seeing your doctors (GP, then referral to a urologist who has all of the equipment) is the best thing to do.

As others have said, consulting a doctor/GP is probably a good idea.  I'm just wondering how much water you do drink?  Living in the mountains and a high-desert climate like I am I think people are supposed to drink 5-6qts of water per day, other places if you're not drinking a gallon a day you're dehydrated.  So I do kind of go pretty frequently, but then I'm not keeping a strict accounting of just how much water I intake. I have heard from people that have lived longer in Colorado than I have, that while you're working up to it, you will urinate more frequently, but once you're at the right amount and your body stabilizes it goes down to normal. 

I will say that I usually have to pee after a good session.  Something about the massage just helps things along there!  I'm a big fan of hydration in general, but for your instance...who knows? 

Am the same as you, have to pee alot after a session. I assume is to do with all the tensing and muscles used down there. 

I also almost always have to pee after a prostate massage session.  I also make sure to pee before so that any precum activity has a clear path to go.  I think that the peeing after is a result of kegels that I routinely do during the session to engage the Aneros inserted on my prostate, plus the other muscle movements.  My sessions are normally about 45 minutes long.  I try to connsume 60-80 ounces of water a day, in addition to morning coffee and an occassional early evening light beer.  The variability of water consumption is usually related to exercise activity, outdoors/indoors.