The BH and Elbow days are long days away from Caye Caulker, virtually 12 hours each. You'll be doing your deepest dive of the trip as the very first. And after those two days you won't want a 30ft dive at Hol Chan on the third day.
Depending on how current you'll be when you arrive, I wouldn't bother with Hol Chan. I'd do two days of relatively local diving outside the barrier reef, and that will be where they take you rather than sites you select, and maybe the BH trip on day three.
It'll take you at least half a day to get to Placencia from Caye Caulker, and to get any serious chance of seeing whale sharks you need to allow two days. Similarly, to get to Glovers will take most of a day (to get back will take most of another day). And after Lighthouse you'll find Glovers a bit of a disappointment.
You're trying to cram way too much into a short trip. I'd probably stay the whole time on Caye Caulker and dive from there. BDS is your best bet.