Hi shouldI - congrats on your new baby! I wouldn't worry about this too much, your supply will soon catch up with whatever your LO needs. If this is just a phase and he/she then wants to go back to feeding more frequently overnight, then a couple of days of that more frequent feeding will soon up your supply to what your baby needs. If it isn't a phase (and lucky you if not!), then again, your supply will soon settle down so your body is making enough for what it is anticipating your LO to take but not too much excess. So don't worry, the enormo-boobs and expressing won't last too long - I would just keep doing what you're doing for now and things will soon sort themselves out - it's all very clever!
Yes, your supply will quickly catch up again if you do need to go back to night feeds. I had a bout of this with DD and used to wake up at 1 in the morning with rock hard boobs. I used to express a bit overnight to be comfortable and also to keep my supply up.