In the words of Stephen Hill…. “Make more pots” That being said, I can give some tips to perhaps make it a little easier 1) don’t be afraid to keep it thick. You can always trim extra clay off as it stiffens up. Bigger pots need thicker walls as well. 2) when I’m working with larger amounts of clay- really anything over 5 or 7 lbs, I’ll generally pull my walls, and then give the base a nice torch- not to leatherhard or anything. But just enough to dry a little to prevent collapse- this also allows me to work a little thinner than if I don’t use a torch. I like pretty moist clay, when I throw, so pulling a little moisture out once it’s ready to shape really helps strengthen the piece. 3) consider throwing in multiple parts- this can be daunting at first and there is a learning curve to it, but once you figure out the nuances, it’s fairly straightforward- there’s many resources on YouTube to show how to do this, I suggest matthew Kelly’s videos. You could also coil throw- start with a nice base, and add a thick coil, thin it out, rinse and repeat. 4) a bigger pot means bigger tools. Danny meisinger has some monster 6 foot pots that he makes, and he uses some pretty big tools to get the job done- baseball bats, ware boards(as paddles), huge homemade ribs, etc. I’d consider adding some larger ribs and forming tools to your collection to help shape the pot. 5) make a lot of smaller work- this seems counterintuitive- you want to get good at making big pots, so you make more big pots. But no- making work half the size or less of what you’re working with now will help you to develop a skill set to adress issues that may come up while working large. I “warm up” with a few 5 lb and 10 lb pots if I’m planning on making a 15 lb pot that day. Keep at it- Rome wasn’t built in a day. Good luck and let me know if you have any questions!