It's more than you're leaving BT up when it could be pressed earlier in the CS (also to keep Enrage going).
BT > CS > RB > BT > SB > RB > BT
Bolded is the CS rotation. What you're basically doing is 'wasting' a RB by leaving BT up a global longer than it should be , I believe.
This is correct. You should only ever have 2 GCDs in between Bloodthirst. The only time this is not applicable is when doing sustained AoE via Meat Cleaver (in which you use BT to maintain Enrage and for rage as needed), or during Bladestorm, when it is acceptable to push it back 1s for Single Target (until Enrage ends) or until Bladestorm ends for AoE.