Booking a hotel room for you both so soon kind of forces the issue. Would have been better to spend more time getting to know each other first i think. If not telling your mum is giving you all this stress then tell her. She'll ask where you're goimg anyway. do you live with your mum. I can see this is all going round in your head like a whirlwind. Your mum's going to find out anyway so just tell her. So she tells you you're wasting your money and reminds you of past relationships. so what. Get your head clear before you go. Go with an open mind, relax and hopefully you'll have a great time.
Ps . Don't live your life in "What if's". What if i say this then she says that and what if she holds it against me and what if........Get it all clear in your head before you go.