I totally understand where you're coming from, Copper350
We're taking a 12 day trip almost the same exact days as you are.
We also contemplated going to Belmont, Port Antonio and some of the surrounding areas for a few days, just to explore more of Jamaica.
We ended up opting against that. This is only because we haven't really experienced all of Negril yet. We took our first trip to Negril less than a year ago. We've only seen a fraction of it. We don't even know what happens when you walk LEFT of the Grand Pineapple on the Seven Mile strip. There also happens to be a lot of fun boardie events happening that last week of April that we really don't want to miss. So many boardies I've wanted to meet and all together at the same time!

I know that on our next trip (whenever that may be) We REALLY plan on checking out PA and other areas of Jamaica.

How many times have you been to Negril? If you've got a lot of trips under your belt, you should definitely follow that urge to explore. It sounds like Port Antonio is really calling to you. When do you plan on going back to Jamaica? If you're planning another trip soon after, then I would say stick in Negril for all the parties and go to PA next trip.

I understand your concern about traveling solo and your budget.
It seems like you've been really conflicted about this for a while,Just follow your heart with this one.

Maybe you should play it by ear. Leave 3 days open. See how you feel when you get to Jamaica. If you feel like staying in Negril, then you should stay. If you feel like going to Port antonio, you should go.

Good luck making your decision. Whatever you choose, you know you're going to have a wonderful time!