Operations looked after ship operations, including sensors, communications and computer systems. But if you wanted to have them more ship focused and give sensor control over to a science officer, then I could understand that.
Flight Control needs to cover both helm and navigation, I never got why they were separate in TOS. I find it a bit odd to split up Tactical though. One officer to handle all weapons makes sense to me, though split it from Security and have a separate Security Chief.
If you're still having Troi, you could strengthen her role by making her Comm Officer in addition to Counsellor. Make more of her as a Diplomacy/First Contact Specialist as well.
As for a contact point between away teams and the ship, that would be the Comm Officer.
Though, using the information you put up, you could try something like:
Operations Manager (ship-based matters)
Helmsman (pilots the ship)
Navigator (handles all sensors and course plotting)
Tactical Officer (pew-pew)
Communincations Officer (link between ships and teams)