If you are looking for a date palm, I would suggest a regular date palm or a Cretan date palm instead of Canary Island Date Palms. None of the date palms are truly 100% hardy in Dallas in my opinion, as the record low there is 0F and I've not heard of any date palm surviving less than 8F (a probably false report about a Medjool date palm). They are pretty pricey if you buy a mature specimen because they grow very slowly, but seeds are VERY readily available and germinate quickly and easily. That being said, they are easy to find, grow from seed, or replace, so go for it.:) You may also consider attempting to find a suckering plant as the suckers tend to protect each other from cold snaps, and only one of the stems needs to live to preserve the plant and shoot off more suckers.

I didn't realize reed grass was anything special or tender, since it's everywhere here . I pulled mine out because it grew too tall in my garden. Replaced it and some other too tall grasses and shrubs to make room for hardy palms.

Polar bear, I only have a handful of palms that get sooo big eventually that they get thrown out of the house...Phoenix, Washingtonia, Butias, and Tracycarpus. Sure, pot size will constrain their growth, as will a lack of optimal growing conditions...SUN, HEAT, FERTILIZER, and WATER (in the growing season). If you want something faster from seed, try Washingtonia Fan Palms (many of mine started from seed). I also suggested the feather palm Butia (they grow like weeds on steroids!). They are quite cold tolerant btw, so as long as get are freezing or above, they are fine in their Winter abode. Occasionally, they get top dragged out in midwinter to get hosed down, or I will cover their contains with snow to get some moisture, but they are largely dry, dry, dry, in Winter. I like them too, they don't seem to mind NJ's ridiculously high Summer humidity and rain, as do many Phoenix/Date palms. I see your palm is inside from your post. That us one reason you are seeing slower growth. They really are not indoor palms... They wanna be outside in the sun and other elements. Mine are out from about March 1 to early December. Adults are okay with some degree of frost and our growing season, even heat, tends to linger well through Autumn.

I think of the two, CIDP will proove to be better suited to your conditions. The problem with Medjool Dates (palms native to North Africa) is the fact that they are not crazy about very humid, wet climates. I don't think they appreciate either hot & wet or cold & wet. I believe pympy dates are more tropical in origin so prefer the more humid conditions (but are probably not cold hardy enough for your area).