Just started on neocate, need advice re stopping expressing?

[Nirish]

My 8 weeks old son has just been started on neocate due to lactose intolerance, he is only having it via ng tube at the moment, but hoping to get him home next week on bottles. I ve been told he will need to be on this for 3 months before trial of normal milk. I am still expressing at the moment but not sure what to do, don't think I can continue for 3 months. Any advice would be useful or if someone had the same experience what did you do?