General questions and first vacation on Naltrexone

Over a year ago I tried one of those Hers weight loss medication kits and it included daily morning and evening doses of naltrexone. I didn't like the way it made me feel so I cut out the naltrexone but at the time I was intrigued by how it impacted my excessive drinking.

Fast forward a year of pretty much daily drinking, if not daily drunkenness, and after doing some research on TSM - I decided to start taking the leftover naltrexone to get a handle on things. The pills are 12.5mg. So far, I've taken it 6 times an hour before drinking and it's pretty amazing how I can have a few drinks and just stop. Some drinks don't even taste normal. The only problem is I just don't feel good when I take it - even at that low dose. I get so tired and just feel off. One night this weekend, I went to bed at 7:30pm after 4.5 drinks and slept for 12 hours straight and then stayed on the couch all of the next day. Is this normal? Will this go away? If 12.5mg works for me now, will I need to up the dose eventually?

I'm going on a cruise at the end of the month and the idea of moderate drinking and actually remembering the entire vacation would be so great but Im also afraid of taking this every day (multiple times a day?) and feeling like garbage for the entire trip. Obviously, not having drinks is not any option. Any advice? This is working for me and I'm really excited to see where this goes but I'm nervous the vacation will derail me.