”An additional challenge is that at home, when 'rehearsing', I sing at lower volumes - but in clubs, with adrenaline + the fact that I tend to go for big chorus songs that draw others in, I tend to belt it out at a fair whack, and so my voice behaves differently.”

That’s a common problem, I’ve lost count of singers who get part-way into a song then realise that the key is too low for them to be able to project effectively, and have to stop and re-start in a higher key. Their usual comment is, “It was fine at home”.

Always rehearse at the volume you intend to perform at - if you have the key too low it will quickly become obvious and you can get it sorted at home and in private and avoid embarrassment in front of an audience.

The usual disclaimer applies - IMHO, YMMV.