I have also heard the the low GI diet is the healthiest 'diet' to follow if needed thru out your pregnancy.
In my first trim, the only thing i really wanted to eat was lasanage, spag, and other tomatoe based foods. I used to be huge into veges, but, i went right off them. Partly i think because i couldnt of been bothered taking the time to prepare them.
I was worried as well that my 'not eating healthy' would do damage to the baby, but, i wasnt major vomity, so, at least what i was eating, mostly was staying down. And my theory is that was better then forcing my self to eat what was good for me, only to have to throw it up again - KWIM. With my tablets, instead of taking 2 everymorning, i would perhaps take in the evening, when i wasnt feeling so bad, or take 1 i the morning, and 1 in the evening.
Even know, with multivitamins, i find its better for me to have them at the beginning of my meal/breakfast, rather then the end, as that swallowing motion of tablet seems to have a bad effect on me.
Drink lots of little bits of water during the day, try icy poles as well maybe if ice gets to boring.