According to the PI sheet, the Stevens-Johnsons Rash will be accompanied by a fever and itching. So if you have no fever and no rash, I wouldn't stress about that. Honestly. Even if you DO get the dreaded Rash, it just involves dropping Lamictal immediately, and you'll be OK. People who die from SJR are the idiots that get a rash, high fever, and don't call their doctor for a week. Remember, and this is true on ANY anti-convulsant, it's just a higher likelihood on Lamictal: ANY rash + itching + high fever = you at the ER with ALL your pill bottles in hand. Nearly every AC can cause SJR, just not as often.
If you are having problems with... well, not sure what to call it, but the disconnected feeling, I'd call your doctor and ask if you can cut it in half and take half in the morning and half at night. People who are taking depakote start at 12.5 a day, and work up from there, so it certainly wouldn't hurt you to ask if you could do that.
Also, a scout of the PI sheet will tell you that anyone taking Lamictal has a 1/10 chance of getting any kind of rash. Not necessarily The Rash, but just a rash. So going hypoallergenic on all your lotions and other body products would probably be good here.
Since Lamictal tends to be good on the depressed side of the scale, if you tend towards mania and don't have a good antimanic in place you could get manic off Lamictal, even a small dose. I know that 25mg difference one way or another on my dose at one point would throw me manic. So your anxiety could easily be from that perspective as well, and that would be another good reason to ask your doctor if you can start your doses smaller or split them.
What other drugs are you taking? <If you don't mind me being nosy.> Lamictal is sort of the "prima donna" of meds, and reacts with just about everything. It will even react with your birth control pills if you are taking birth control. <Seriously, it's in the PI sheets.>
I wouldn't freak out if I were you, but I'd still call your doctor and ask.

It'll be OK. And Lamictal is seriously one of the best drugs out there, give it a chance. <And make sure your lotions are hypoallergenic!>