FET prep (diet related)

I’m officially nearing my first retrieval after 2 years of ttc and ivf! However, with covid, of course, my job doesn’t make things easy. I work with kids on the spectrum in a 1:1 setting-we only receive 15 minute breaks and get to leave early as compensation (they are trying to reduce the risk of crossover between staff, kids and rooms). Due to this, I don’t really have a “safe” place to eat. To put my best foot forward, I want to find a good meal replacement shake that can supplement a lunch and not risk my health during a transfer and possible pregnancy. Does anyone have any good recommendations of pre-made protein shakes that have enough nutrients that can cover you a few hours until you get home??