I actually never used the Ls, I started with the CLs, and when I started with them they were DEFINITELY big enough! Even now as I type this I am noogling with the CLs and I almost fill them at the size I am now. The CLs are a great size, I think.
I am literally just recently able to put the XLs on without them farting off, or having to hold them in place for 15 mins or so - they're VERY big, esp. if you are small in size as a person, regardless of boobs. I'm a 27 underbust, so it's tough! And as I said, I am at the 3-4 inch mark on those, and they go pretty much up to 6 or 6.5 from the looks of them, so I still have probably a year or so to go before I'm near the end of them. The best thing about them IMO is they are bigger at the bottom and can suck in more circumference, which has helped round me out more. But for more outward growth, the CLs are awesome.
If you're outgrowing the Ls, I'd rec the CLs first, or maybe get both - but the CLs will fit better than the XLs is my guess.