Ay, congrats sa 20 weeks! Hindi ko sinasabing bawal ng buo, pero ang concern talaga ay sa caffeine content ng milk tea, sobrang dami usually, lalo na kung mataas ang level ng tea, at doctors generally suggest limiting caffeine pag buntis kasi it can affect the baby. One of my mum friends naman had to cut back kasi nag-worry siya, pero honestly best check with your OB mo kung magkano exactly ang safe para sa iyo since every pregnancy is different, then you'll feel more relaxed about it!