Susie--
this is really something you need to address with your neurologist. If the falls are the quantity/severity of needed ER or Hospital attention, it needs to be addressed quickly. I understand that if you lower the dosage you may have more seizures, but just from your post I gather your seizures are not 100 % controlled either--hence Lamictal may not be the right medication for you. There are many, meany medications and options for treating epilepsy and seizures-- talk with your neuro about it and come up with soloution or plan of action on.
On somewhat different note, I am curious as to what make you think that the falls are solely cause by the Lamictal not caused or aggravated by any of your other meds, especially neuro meds. I am not doubting what your saying, so don't take it that way-- just throwing out some thoughts. Like you, I am on multiple meds for seizures AND other neurological issues. All meds that effect the nervous system have unique effects on the body and when you combine several of them together the chance of developing side effects--- either more extensive one you already have or new ones from the combination is much higher. I am living proof. There was a time when I was on Depakote, Keppra and Lamictal for seizures, and Elavil for nerve pain and I experienced signifigant tremors and was forced to lower the Elavil doses. After I got off Depakote, the tremors subsided greatly and I was able to increase the Elavil with no major problems. I also had some nasty reactions to medications that I probably never would have had if I weren't on multiple meds. Often times you can keep the various meds, but your dosages may have to be altered some so you can get the best help from them with the least amount of side effects. Don't discount the possibilty that the falls could be a combination of things.
So, please discuss everything with your neuro--falls can be really dangerous---and sometimes more so than seizures, so this side effect is not one to take lightly.
Good Luck !

L2L