You could try changing the string for a metallic wound string. It's louder but personally I find the sustain issue isn't as big an issue as before, and also the metal string doesn't sound much different from a nyglut one. Buy some Aquillas, I did for my tenor and never looked back.
Another tip that you can try without changing the string is, muting the string with the palm of your strumming hand near the bridge, or trying your best to strum all string evenly. The only other thing I can think of is to use your nail, it's far more noticeable when you thumn strum.
Because I've been playing for so long now you don't even do it consciously. From what I've been told from people listening to me play (uke players and non-ukers alike) it's far more noticeable to you.
