Dantastic , think carefully on what I'm about to say it may fit you very well.
Don't be fooled don't get a fish at this stage, look for a higher volume fun board of better quality than the old trench board you have now, a bit more width a bit more thickness under your chest.
Why, fish boards are made to throw around in fairly crappy surf and start to fail in their ability in better surf for the average guy>. A good fun board or a sort of universal high volume medium shorty would be a better option and suit more wave types.
I read through a lot of your posts to see where you are really at in your surfing and IMO you are better off stick to more functional over a wider range of equipment than being swayed by things that on the surface look cool. Your journey at this stage would suited to getting an all round set of skills not backing yourself into a frustrating corner.Perhaps there is somewhere you can beg borrow or hire a fish and see how they fit before laying out cash for something you will need to sell on.
You have not reached the optimum performance on a fun board ( I hate that term BTW it belittles a slightly larger all round board).
Going short unnecessarily is falling victim to the fashion side of surfing.
I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun!