(My dims: 21, 5'11, 150lbs)
To give you some background, I started surfing last summer, and I've had no problem getting up with my 7'6 fun board on head-high and lower surf since day 1. I can trim pretty well, but I've never attempted carving before.
Out of need for something shorter than the fun board, I recently picked up a 5'10 21"x 2.68" EPS groveler-shaped quad (5 fin box) w/ approximately 35-37 liters from a local shaper @ West end Long Island for about $550.
I picked something this wide with consideration for how choppy/pitchy the waves are here, and how the swell's seldom over 3'...
Honestly, I was talked into buying it by the shop keeper when I went in asking about fish boards, and at the time he DID tell me that I COULD go shorter than 5'10, but that I shouldn't worry about it b/c everything else about the board was fine for my dims and that I should still be able to duck dive it etc..I was too scared to shorten it down tbh, given that I've only ever ridden a 7'6 and an 8' before this one...anything below 6 felt daunting as is.
He told me that a squash tail groveler-type would do me better for learning the back-foot fundamentals necessary for shorter boards than a fish that traditionally handles front-foot-heavy
I only question the board choice because I've been reading around the internet for a while, and I'm starting to wonder... Isn't this groveler over-sized for someone with my dims in respect to volume and height..?
I've tried to duck dive on it, and it's pretty damn difficult..maybe I just suck, but the board barely sinks under me at all in the water, let alone when I duck dive. I have a pool, and I've tried practicing there, but still it's really tough to get the wider part of the board under, even while trying the scooping method, I just seem too damn light to do it
I was able to catch a couple waves, but it just doesn't really seem to have hold in the wave, it seems to skim on the water underneath me and I'm wondering if it's because it's an EPS and I'm used to poly, if it's short boarding that I need to get used to, or if its got too much damn volume for someone with my weight?
It's hard to tell if this is a good short board to be learning turns and carves on

What do you think?