:( I'm really sorry you're having so much trouble, I wish there was something I could suggest that would make it magically smooth out. Seizures suck.
If you're tired and struggling, maybe it is right to get signed off for a few days, just to see if you can sleep? Your toddler won't come to any harm in a closed room with you on the sofa and them watching TV - and maybe you can snooze a little? Paracetomol is quite good for pregnancy aches and pains if that is part of what is stopping you sleep.
The end of pregnancy is so tiring, and a lot of us really struggle even without chronic conditions. The tiredness gets you down, and means you're so much less well equipped to stay cheerful when even minor stuff happens. But you know the condition, you're just so tired it's tough to deal with it as well as you normally would. It's not going to last - after pregnancy your hormone levels and weight will get back to normal. So this is a big push for a very worthwhile goal. You'll meet your new baby and it will be worth it in the end.
OK, the only suggestions I can think of:
Maybe it's time to get your levels done again? Even if it takes ages to come back, at least you can look forward to an answer sometime soon. Remembering an old thread, your levels had gone really low, so maybe it is happening again? You could see if your GP would be willing to do them every 4 weeks so at least you can tell if there is a trend of them dipping this pregnancy, and you always have a recent set of results 'in the bank' for when you don't know what's happening? Are you putting on lots of weight? (Such a personal question!)
Anyway, big hugs, sorry you're having such a rough ride. It'll be worth it in the end - honest!