I had severe OHSS and so can tell only you what I felt. I felt very bloated, so much so that I put myself on bedrest and had to lay down flat, even propping myself up on pillows was uncomfortable. I was trying to drink the 2 litres of water plus 1 litre of milk thing, but physically could not stomache it. I lost my appitite and felt very sick and was eventually sick. I also felt very gassey, but like you, couldn't pass a bowel movement. When I was admitted to hospital, they got me to try to pee as I hadn't been for several hours. I managed to squeeze a tiny bit out, but nothing in relation to how much there should have been. I then had to have a catheter in to measure it. My tummy expanded by 23cm in just 2 days, so yes, I was VERY bloated! My 2 day transfer had to be abandoned and now I have 3 snowbabies waiting for me out of 34 follies and 25 eggs.
I hope for your sake that you don't have OHSS. Your ovaries will be very large (mine were 12cm each) and you have had lots of invasion inside, so uncomfortableness should be expected. If you think it's more than that - the non peeing is a very good sign to look out for, then get yourself checked out. I called the clinic, and they said it all sounded normal, but I knew I didn't feel right, so I got myself to the hospital, only to have a drip put in straight away and then to be moved to the ICU the following day as my blood chemistry was just deteriorating. So, my advice would be if in doubt, always get checked out!
Best of luck!