Early pregnant going on holiday

Hey, after some advice please.

I think I may be pregnant as I have a faint line on a test today. I'm going on holiday in a week with about 8 people and I obviously won't be able to drink if things work out. They know were trying for a baby and the reason I booked this holiday is because we had been trying for over a year and it was last minute as nothing had happened... So now I may be pregnant I'm obviously so happy but it's put me in an awkward position. They will know I'm not drinking as I'm usually a drinker! Any good excuses I could use? A few of our friends have used the antibiotics excuse so I cant say that. Also I had a miscarriage at 5 weeks last year so I don't want to tell anyone. Thanks.