You're not being a bridezilla - once of the things that sold our venue to us was that I fell in love with the guy who would be doing the co-ordinating (also the owner, it's a small husband-wife team). He was just amazing, and I know that if anything goes wrong on the day, he will fix it and probably give me a hug and tell me it's all going to be fine!
Throughout all of my supplier choices, I have looked at price and quality of course, but the vibe I get from the suppliers has been a deciding factor in many choices we have made, because we don't want to be surrounded by people that make us uncomfortable on the most important day of our lives.
As to what you can do about it... firstly, maybe have a little chat with her. If she's so new, she may not realise that she is being off-putting, and she may well appreciate some constructive criticism on how she could conduct herself. Be friendly about it, but it's important that you feel comfortable with her. But we all have to start somewhere!
Regarding the fact that she keeps checking things - I don't think there's much you can do. She's new and probably still learning the ropes. It's better that she checks and gives you the correct answer than promises something that can't be delivered.
If you chat with her and she refuses to change her behaviour, then I would approach the venue and ask if it is possible to change, or for you to have a reduced price and organise yourself if possible.
Hope this helps! x