Sayang, cyst during pregnancy boleh jadi scary, tapi yang paling penting sekarang adalah kena check dengan doctor dulu untuk tau exact situation mu, some cysts okay je, tapi some kena monitor closely. Regarding milk/susu, honestly standard prenatal milk should be fine, tapi please confirm dengan OB mu dulu what to avoid based on your specific cyst situation, sebab tidak semua supplements aman untuk every condition.
A few of my mum friends had similar worries and their doctors actually guided them on what's safe to take, so jangan self-prescribe lah even if it's just susu. Take care!