Much like your injuries, this is going to take time to heal. I commend you for getting back into the saddle again, but I can't tell you when it's going to get better/comfortable for you, as that depends on you. I can tell you a little about my own personal experience in hopes it can give you some indication that you're definitely not alone here.
In 2009 I was riding my mare who is green, but rather brave, with my other mare and friend. We were socialising Honey under saddle for the third time, and it was going really well until we separated in my paddock for own on pursuits- Honey wanted to trot, and was happy to do so until she realised her friend wasn't beside her anymore. She panicked, rushed to my other mare, who booted at her. Honey then went into panic mode and bolted. I managed to fall off and shatter both bones in my right leg - I'm now part bionic. It took me 8mths to be able to walk after the accident and I was pretty much ready to throw in the towel. I felt like I'd never ride again, just the thought of it made me break out into a sweat and send my heart racing.
It was actually my horses that got me to calm down. I didn't get back up until early 2010... but I spent as much time (even when I couldn't walk) hobbling around my horses as I could. I found just spending time petting them, and then having the ability to look after them again really made me get back into the swing of things. I started to crave more, and started doing everything I could. I started to dream of riding and when my friend got back up on both my gelding & mare that was enough to make me determined to decide. I told myself if I freaked when back up in the saddle, then I was going to sell my babies and move on. Thankfully for me, my mare was just as determined for our partnership to continue and was a saint who gave me some very nice led rides. After that I just built up to riding by myself comfortably. Sadly Honey had some unresolved issues that we thought we had addressed, but were hidden and a "professional" caused more damage than helped her. It took until this year to bring her back into work, and she's still not completely right. However, I can handle everything again back in the saddle without breaking into a sweat or riding in small spaces in fear of bolting.
I should mention I was already a relatively nervy rider. I'm so happy to have a mare who really takes great care of me, and we've learnt a lot from our mistake in 09. It takes having a good partner in a horse, and some great support around you to get passed things that are currently stumping you. I'm guessing your instructor is providing you with the support you're needing? Have you spoken up about the nerves you're experiencing? This won't fix over night, in fact you'll have to push yourself harder than you ever have. If you want to ride again, and do so at a level where fear isn't preventing you, then you'll need a lot of determination, support, and trust in your riding partner.
I wish you all the best. It sounds like with time you'll be back to feeling like you can ride comfortably!!
♥ Seoul Searchin' for the Lovebug ♥