I would not be worried about your blood sugar results either. I too had problems with my vision (and still do). You can get vision problems if you are stressed too. My eyes are perfectly healthy and I go for retinopathy screening once a year and an eye test too, please make sure you do this. I have always had perfect vision so it's hard to get used to these changes, but it doesn't necessarily mean there is something wrong. One thing I found helps my sight is Retinex from healthspan, try it.
Please, go for your hen night. I wasted too much time thinking about all the what if's and this and that, but life really is too short. Go out, have a good time, be yourself, enjoy celebrating your friends last night of freedom. Just be mindful that you do have to consider your body and keep your wits about you. Try drinking wine spritsers, that's a glass of wine with soda water and it makes a little go a long way. I also like tequila and soda with a slice of lime or rum and soda. Whisky and diet coke if you like it? Try to nibble on some peanuts if you can - a great way to keep you stable and mop up the alcohol. And make sure you eat a meal before you go out (not too much carbs, maybe an omelette?). Don't be embaressed to go on the water if you feel like it, I sometimes have to do that as I'm a lightweight anyway. If you do those things, you can't go too wrong, honestly, I've been there!
In the morning, try to enjoy a good protein breakfast, a fry up would be a good option - I'm guessing you'll be away for the night? If I was you, I would probably take some nuts in my handbag ( just in case there is nothing to eat), this will put your mind at rest.
Try not to expect anything, if you try to listen to your body and take it steady, you'll be o.k. Don't assume the outcome before you've even got there, you can only do your best.
You'll be o.k, I'm sure!
Have fun and have a laugh XX