Congrats on getting your baby on such a great sleep schedule at 4 months!
I went through the same thing with my baby girl. It sounds like your little one dosn't need that last feeding, so unless you want to keep pumping to store your breastmilk, you should be fine dropping it.
For me, sometimes Chloe would nurse well right before bed and I would be fine skipping pumping, other times she wouldn't drink as much and I would be uncomfortable in the night and need to pump.
One thing to remember is your breasts should NEVER become uncomfortably full! This puts you at risk for plugged milk ducts and mastitis (breast infections).
It sounds like breastfeeding and pumping is going well for you, so there is absolutely no reason why you should have to be uncomfortable or in pain!
If you start to feel uncomfortably full or engorged, just pump until you are comfortable and then stop. This allows your body to slowly and safely reduce your milk supply without unnecessary risks to yourself.
Good luck! :)