Falling sucks wind, there is nothing more scary to me then falling off lol I fell last year, well I kind of took a dive really, pulled a one reined stop my first but I felt myself slipping and decided this was as good a spot as any to land on lol I ached for weeks after (I'm 46) and for at least 6 mos I had a tenderness in my shoulder. Those aches and pains kept my fear levels up and I didn't ride much after that, just helped everyone else, I made myself ride him a few days later just to make sure I wasn't afraid but I have to admit I really wasn't feeling it with this particular horse.
I just went on my first trailride a week ago, it was heaven. I let that gelding rob me of my confidence.
You can do this but there is nothing wrong with waiting on the trainer to get back and having that for support to get you over this hump.