Trying to find the right board

I am 14 years old, 4'10, 90 pounds, and I am trying to find the optimal board size for my skill level and weight. Right now I have two boards that I use, a big Costco Wavestorm, and a 6'0 shortboard. I've been surfing for about 5 months almost every day and I can surf both surfboards pretty well but they aren't ideal for the majority of my surf sessions. The soft top is really nice in terms of paddle power and ease of popping up, but once i'm on the wave I cant really do any turns because i'm so light. The only turns that I can do on this board are when I for example angle my board towards the beach if there's an end section. My shortboard does work during some sessions but most sessions it feels like there's not enough buoyancy and I end up missing out on a lot of waves because of that. When I do get on waves, I can usually turn pretty well. I put my weight on by back foot and aim for the sweet spot right in the pocket in between the breaking wave and the soft shoulder. The problem is that most sessions i'm just not getting enough good waves to try that out. I used to have a 7'4 funboard with a little bit of rocker that worked pretty well before I dinged it up. I had more than enough paddle power but I couldn't turn it very well. My biggest strength is wave catching, and I've lost track of the precise number but I know that I've caught more than 20 solid overhead waves (for my size, which is about 6-7 foot). My weakness is my popup, because I have a bad habit of using my knees which has worked most of the time so far but I know it's a big issue I need to deal with. Most of the time I surf a spot that's for beginners that now has a perfect sand bar that makes it peel perfectly with medium steepness for about 1/2 a mile. Most days I'm the best out in the lineup, but some days with lots of experienced longboarders out I'm the 3rd best. I sit way outside and only catch the biggest sets. Sometimes I also surf a reef break that breaks right in front of a cliff and is pretty steep, but I only surf it on days under 7 feet. Also I'm goofy footer which means in my town i'm almost always surfing backside. Anyways back tow the original point, what board would be best? A fish? A step up? Something else? Thank you for reading and sorry it took so long.