Hi Nakkie,
Congrats with your pregnancy.
I dont see a problem with replacing a meal with a shake, just as long as you get all the nutrients you and baby need. I got my mom2b shake samples a few weeks ago. they do taste great and is specially formulated for pregnant and lactating mommies, so they kept the nausea factor in mind.
In the beginning of this pregnancy i too struggled to eat, and still do im 23w3d.
yet i force feed at times, only smaller portions.
good luck!! and enjoy your pregnancy!