I had this with my DD. She has just turned 3 (and finally potty trained!) but she is currently wearing age 4/5 clothes. Has always been a year above her age in clothes size and outgrew her Bumgenius and a lot of the BTP nappies pretty early one as she is so tall too.
I used Wonderoos and Mommys touch with her. Wonderoos can be well stuffed to deal with the worst toddler wee, but they are more bulky and if they were not put on exactly right she got builders bum with them
but they were so reliable I lived with that. Is easier with a girl though as skirts make big cloth bums easier to deal with.
Mommys Touch were good too, and with a hemp booster added would last a good 3+ hours. You can also buy extender tabs for the poppers although thankfully I never needed them. They are a trimmer fit for under trousers.
Happy Heiny one size also fitted, and have seen some recommending them because of this. I found that the inserts, even with boosters were not up to toddler piddling though, so only used ours as a last resort nappy.