I chose her because she's young, healthy, enjoys trail riding, and I was assured she would be a safe mount for me.
I guess my first question is: Who exactly was it that "assured" you she would be a safe horse for you?
Are you working with a trainer?
Ended up adopting a young mare from a rescue. Her name is Pearl and she's about 7-8 and believed to be a Tennessee Walker. She needs some work but she seemed very responsive to me during our test ride. I've only had her for a couple of weeks and haven't ridden her much at all during that time. I've mainly been doing ground work with her.
Ground work is fine and gives you an opportunity to get to know your horse, and of course work on any ground manner problems. But if you bought her to ride, well, as some point you'll need to saddle up on a regular basis!
How long will it take for me to build up my confidence with her and how long does it usually take to really bond with your horse?
I've been riding horses for almost 30 years. For myself personally, I don't really like the word "bond" to be used to explain the relationship between a horse and a human. I think horses can certainly learn to trust and respect their human handler, but in my mind, they are an animal with certain instincts and their own personality characteristics.
Rather than the word "bond", for me it's more of a matter of how long it takes to me to get to know the horse inside and out and know how the horse is going to react in situations. With my current horse Red, I'd say it was a good year before we got over some of our issues and I knew I could trust him. With my aunt's horse I borrowed last year, heck, I was sending him over jumps on a loose reins in just a couple weeks, trusting that he would go over them and not balk and/or refuse even though it was new to him. Every horse is different.
There's no way to answer how long it will take. You'll have to progress at your own pace. Not only will you have to get to know your horse, but you are going to have to overcome your previous bad experience. Do realize, if you want to progress, you HAVE to push yourself out of your comfort zone. No one ever learned anything by staying comfortable!
I would really like to learn to love her, but part of me is worried that my anxiety is getting in the way of really bonding with her and learning to trust her.
Not only does anxiety affect you, but it will negatively affect her too. If the horse senses that you are anxious, they will be less likely to trust you. So it's a two-way street.
You will have to find a way to manage or eliminate your anxiety. Again, impossible to say how long that will take because it is different for everyone.