are these sentences grammatically correct?

Watashi wa mainichi mizu o nomimasu. Demo, yoku gyuunyuu o nomimasu.

im unsure if my placement of 'often' in the 2nd part is correct, im pretty sure its not but i kinda feel that it is x.x~

ur words will be understood correctly, but could be better by fixing a little.

since milk is compared with water, "mo" is preferred to "wo (o)".

and it sounds more natural if u put an adverb ("yoku") just before the verb ("nomimasu").
but it doesnt matter a lot. ur expression isnt so incorrect that i mistake what u mean, but sounds a bit awkward.

thanks, this is part of my oral for japanese(im in hawaii, lots of language courses here), and we didnt cover those things in depth. and we weren't allowed to use things we didnt learn yet but i got a 50/50 on it, had a few flaws but since i was first she didnt care nobody else got a perfect