Breastfeeding & Hyperthyroid

FTM here. Need advise.

I am a hyperthyroid patient who is soon expecting my first baby to arrive in a few weeks . Right now my thyroid levels are under control which my endocrinologist said is a classic thyroid behaviour to go into remission towards end of pregnancy & said that after one month from delivery, my thyroid levels would need to be tested & if I need a PTU dosage which is higher than normal I cannot breast feed .

Hence I only might have one month to feed by LO . While I still don't know if and how my supply would be (though I have always wanted to Bf my baby as much as possible ) , is it advisable to pump ahead and store in case am unable to feed him later , I can use this stored milk ? Trying to be prepared / learned.

Stressed by what my endocrinologist told.