You might be overreacting, but if it's concerning you that much, get it checked. We're all entitled to overreact sometimes :)
Countless studies have shown that a superficial wound heals best when it's kept covered (and this is pretty widely accepted by the medical community). So if it's just a scrape and not something deep, keep it covered and clean. And using bandages and antibiotic ointments to keep out infection helps, too. Keep doing what you're doing - loose, bandages that air can get through and antibiotic ointment.
If you want to clean it every so often with isopropyl alcohol, you can do that too.
As for your vacation... people will tell you salt water is good for wounds. While that's true, all the bacteria and other microorganisms floating around in sea water aren't! The salt does NOT kill all the bacteria! Don't worry too much. Just make sure you flush out your scrape with clean water and disinfect and dry it well when you get out. If you can, smear something like vaseline on before you go for a swim as this will form a "waterproof" barrier around your wound.
Also, letting it scab over won't do much good to protect you from the salt water. 10 minutes in the ocean and the scab will be pretty much soaked off, anyway. Best to focus on getting it as healed as possible before you go, and that's best achieved by keeping it clean, dry, and covered.
med student... I've also endured many cuts and scrapes in my time...