Well, the first thing to know is that my 11yo isn't that much smaller than me. She's about 5'1 or 5'2 and weights around 115. I'm just shy of 5'5 and weigh about 125. But my experience on boards of various sized thus far has been as follows:
9.5 fiberglass board was Way. Too. Big. I was a danger to myself and everyone around me and too scared to even go after waves.
9 ft foamie—actually had great fun on this, could catch waves quite well even though I was a super newbie then, but that board is back in New York. And I only surfed it at one beach, which had smallish, consistent, Waikiki-type waves.
8ft epoxy—rode this nonstop for a couple months, was surfing whitewater and starting to catch waves. But then it needed to be repaired and I started dipping into my daughter's collection and that's where the trouble really started...
7'6—this is my daughter's fiberglass funboard. When I was borrowing it, I surfed it far, far better than I did my 8ft epoxy. Not only could I catch waves, but I could turn! And ride along the crest both to the right and to the left! It was great! I would have happily (and quietly) claimed the board as my own, but alas, my daughter wanted it back, and since it was a birthday present, I had to agree.

7'4—So, I decided to get myself a smaller board. It's a 7ft4 bulky fun shape and although it turns on a dime and I do really like it for catching waves at reef breaks, it's really not suitable for the beach near my house where the shore break is better for shortboarding. (If nothing else, I'm scared of running into a 90-lb 10yo boy. There are swarms of them and they come out of nowhere.

) I'd hoped the 7'4 board would be the "one board to rule them all" and I would ride nothing else for at least a year. But alas, no.
6'6—This is my daughter's short board (though it's not really "short" for her, or even me.) Oddly, I catch more waves on this one than anything else. But I can't *ride* the waves as much as with a bigger board. On a 7'4 or 7'6 funboard, I feel like I'm standing on a table, but with a 6'6, it's more like I'm jumping onto a skateboard. However, I've only taken it out a few times, in variable conditions. And I adore this size when I'm at my local beach surrounded by the Jr High shortboard posse. I'm VERY in control on a board this size, and I know I'm not going to hurt anyone even if I accidentally drop in or nosedive next to a paddling kid. Since I'm not intimidated by the board, I paddle in harder, too, I think. Which is probably why I catch more waves.
The times I do catch waves and stand early enough to turn, I get a sense of why people like Shortboards. They're zippy and fun. I'd love, love, love to get as good at shortboarding as the average 12yo boy around here. As for long boarding...I see the how of it, I just don't understand the why. Long boarding seems kind of boring. But everyone around here seems to think it's the best thing ever. So I guess I should keep an open mind?
Anyway, at this point, I feel like Goldilocks, trying to figure out a size that is "just right." I'd like to only have one board. I just don't know what that one board would be. I want to keep improving, but I also want something small and agile enough to handle the conditions (and people) at my local beach. After all, I'm there 4-5 times a week. If I thought I could ride one of those Sushi boards from Costco, I would. But I think I'm a bit too heavy.
Mostly, I want to stop thinking about it. I want to focus on my skills, not obsessing that my board is too short or too long for conditions. (Because of course dudes at the beach are always telling me my board is too long or too short or that I probably won't catch anything. And I'm like, "I'm just here to practice, at this stage, any time in the water helps.")
So what's your advice? Do I stay on a funboard even if it means I can't catch as much at my local beach? Or do I try to transition to a long-ish shortboard and put up with sucking until I get the hang of it?
Thanks in advance!
Daisy