You can get Graham Cellucotton from Sally's or from Amazon and you need to make sure that you get the box that says 100% Rayon (they also make a 100% cotton version confusingly named... exactly the same thing.
If overwicking is your issue, you may find rayon easier to deal with, it shrinks when wet, and cotton swells.
Also, I'm one of those "More isn't less" people, so I really have to work to NOT overwick rayon even. Tight in the coil is good, and I have found I need drastically less wick than I think I needed.
You may have found your sweet spot with cotton by now, I'm just merely going to note that rayon also burns at a higher temperature, and lasts longer than cotton and can withstand higher wattage.
There's an entire
thread on it if you are interested:
https://www.e-cigarette-forum.com/threads/rayon-wick-better-flow-flavor-longevity-and-nic-hit-pt-2.706948/page-152
Good luck,
Anna