Hi Becca,
As a long term insomniac I totally agree with Cha on this one. DON'T GET STRESSED!!! Easier said than done I know. I think insomnia during pregnancy is very different from 'normal' insomnia. You have reasons that you can't sleep: physical disomfort, going to the loo all the time, worry, precious little one doing an internal tap-dance, and then of course there's the heat!
So firstly, don't let the fact that you're not sleeping panic you into not sleeping. I know that sounds silly, like telling someone not to think of pink elephants... (see what I mean? Cute aren't they) but the more you stress about not sleeping the harder it is to relax.
I find distraction is defintely the best remedy but keep it calm... I don't think watching telly or using the PC is a good idea. These things stimulate you and what you need is to be relaxed. Even if you're not sleeping, relaxing and listening to calming music will give your body a rest.
Lot's of people swear by a warm bath or hot drink, but in this weather I'm not sure if they would help.
If you get very hot, keep a plastic bottle with a spray nozzle filled with water in the fridge. When you get hot, spray yourself with a fine mist of water. I find this very cooling, especailly if you not wearing anything and the window is open!!
If you find you're more comfortable on the sofa, the floor or anywhere else then don't force yourself to sleep in bed. I would never reccommend this for 'normal' insomnia, but as I said, I think we're all in a very different situation and, IMHO, anyway you can get some sleep is good.
Lastly, you are not insane. In fact, as you can see from the other replies, you are perfectly normal for a pregnant woman!!
Sorry if this goes on a bit.. and it's all only IMHO so any professionals out there, sorry if you don't agree.
BR (34+4)