There may be another option. Typically after 6-12 weeks of breastfeeding, supply switches from being hormone-driven to being suck-driven - and expressing becomes more difficult as the total supply goes down to match what is being removed.
I don't know what happens when you are expressing - but I would guess that whatever hormonal kick you had driving your milk has probably gone away now, and you will simply make to replace what you have taken out.
And typically hand expressing is better at getting out the last bit than a pump is. Do you hand express the last bit out after pumping? That can help.
The other thing is that when you are hand expressing I think you have to take little breaks and stop and start - which effectively means more let-downs, and for some women more milk.
Can you talk about this to the LC?