I am unable to confirm the ferry times from La Ceiba, but if it arrives and departs at those times then I think you may be a little tight for time.
Most dive boats depart between 8am and 9am for two dives and return for a brief stop at lunch to exchange empty cylinders, drop off & pick up divers etc and go off again for the afternoon dives.
I think you would not be able to catch the morning dive boats, and would be too late back for the return ferry if you was able to get on the afternoon dive.
I would check out to see if there is a small independent operater who would take you out, as these seem to be more flexible. Failing that, see if you could do some shore diving when your not reliant on a boat timetable. You would have time to fit in a dive this way.