Hello Terry
Looks to me like you are not too far from the truth

Which tippet are you using?Are you degreasing regularly if it is mono/copolymer? Size of flies ?Here on Chew Valley and Blagdon Lakes size 14 seem to top the bill over a season.
5wt would be my choice for reservoir dry/emerger fishing as usually here settled conditions go hand in hand with the fish feeding in the surface layers.You can still fish with a 7wt I just personally find more tendency to open out lightweight hooks especially with fast action 7wts plus a tad easier all round and more in tune with the method using a lighter outfit although do not fish with a lighter tippet than I would on the 7wt.Just my take on it and how I was introduced to reservoir dry fly fishing for pleasure.
Sometimes when fish boil at the fly or near a tweak of the fly will flick the switch.Not always I might add but sometimes
New Zealand/US hopper dropper,hopper dropper cropper set up can be a real killer fished off a buoyant dry fly.
Best JP