Valsmum,
you could talk to your doctor about increasing your folic acid slightly (just another mg or two a week. I have definitely also heard that it shouldn't be taken on the day of the MTX, because it can cause some kind of interaction (not sure if it made one drug or the other less effective or more side effects and I can't find the reference now), but that it doesn't need to be taken every day - its the total weekly dose that matters. Folic acid definitely does help relieve that nausea, so it does sound like you aren't getting quite enough. You do need to just increase it very slowly though until it balances right and you feel better, as too much can also cause problems.