Give yourself time.
Falling off a pony as a child and falling off a horse as an adult is a bit different because it hurts more, the bigger we are, and adults tend to tense up more than kids do when they fall.
The more you ride and spend time with your horse, the more chances there are of accidents, but GOOD instruction can help.
Many of us who are older and have had injuries in the latter years have had our confidence shattered as it takes us lots longer to heal. My last 2 horse injuries took a year, each, to heal . . . but you are young still!
I do not think adults tense up more when they fall at, yes, they are more likely to injure themselves but this is only because for each year you are on this earth the ground gets harder!
Over the years I certainly became more adept at staying in the plate. Didn't mean that I never fell because I did. Didn't mean to say that I never hurt myself because I did. It is just that I was brought up with a different mind set.
Instructors were all military taught, they were respected and feared. You didn't argue, you didn't make a fuss you just got back on and tried again and again if necessary.
I was used to ride the remedial ponies, I chose to do it because the rides were free, if I didn't then I only got to ride every second week.
An example of my Mother's attitude was when, just 14, I took a fall from a gypsy cob mare. I don't know what happened only sitting against a tree watching her big brown and white butt descending towards me and thinking, "This is going to hurt!"
My nose was broken, my front teeth bent back, my lips cut through. I rode back with the ride to the stables where I spent the rest of the day.
I swelled! Despite the swollen eyes I could still see my top lip curled up to my nose so the inside was looking out. This had ulcerated.
My sister and cousin got home before me and when I walked in Mother was dishing up our supper.
She took one look at me, sat on her stool covering her face with her hands peeping out from behind her fingers crying with laughter. Her comment was - "You won't want vinegar on your chips!" (Fries)
I then was made to walk to my GP. Neither of my parents drove, where I got a lecture about not having my lip stitched earlier.
There were no such things as panic attacks, your fear of the wrath of the instructor was to great and stronger than fear of what had happened.
For someone to go out and but a horse after six months of riding makes them inexperienced. If they had ridden two hours a day six days a week for that period it would give them 300 hrs experience in the saddle. More likely to was at most two hours a week which is only fifty hours, by my book a total novice.
This is why a fall comes as a shock, the person has probably never even thought about falling off. It happens even to the best of riders, you either put on your big girl pants and get on with it or stop riding. The more you allow yourself to be nervous the more likely you are to have an accident because the horse will sense your tension and reply to it.