Anna

Firstly congrats babe on BF DS so long.

I think you can easily BF when you are with DS and give him formula when you are away. That way there is no need to express. Don't forget, he is having 5 feeds a day ATM but that may change as his solids intake increases.

My suggestion is to try to get the 'uni hours' feeds to gradually convert to formula. Perhaps try one feed a fortnight. Now I have no personal experience with this so I could be totally off the mark but I think the gradual approach is least likely to affect your supply for the times you are with him. There is no reason whatsoever that you guys can't make it to 12 months if that is what you want.

HTH
Spring xx