wahwah - who the heck has told you that??? Under pressure = milk supply dropping???
I can assure you there is no evidence that this happens, and plenty of evidence that it does not!
Individual experience varies, and perceptions vary, and you may hear people say they are sure this happened to them - but there is no biological reason why it should. Women breastfeed in extraordinary circumstances - just as your blood continues to circulate in times of pressure, your milk production continues. You continue to breathe, and to see, and to hear, and to put one leg in front of another to walk. Making milk is a bodily function, and once established, it is very far from fragile.
If you are concerened about amounts of milk, then feed more often, using both breasts at least, day and night.
That is the very basic way milk is made
taliac's post is good, too, and porridge will not do you any harm, but you prob dont actually need it!