Show Jumper or Riding School Pony?? Why can't I ride both???

Right...
I have been riding for about five years now but in the last couple of years I have had serious confidence problems (not from anything major). In the end I left the stables and had a year off riding. I began riding again at the start of this year and felt like my riding and confiedence had come on in leaps and bounds but then up comes my problem...
My instructor recently put me on her Show Jumper who is between 15 and 16 hands high (I'm not 100% sure) and as soon as I got on him my riding changed dramatically. Not only wouldn't I canter him I would only just be able to control him in TROT!!!!!! This is odd for me as I am in the top group at my stables where I should have moved on to cross country fences. It has gotten so bad that on one of the hacks out I burst into tears and had to get off the horse.
Everyone else says that I ride him really well but I just feel like my entire knowledge of riding just flies out the window and I feel like a beginner again. I am used to riding the typical riding school horses that are slow.
Any advice is welcome on what I can do to ride the show jumper. I do want to ride him as he is a sweety in his stable and I want to enjoy my riding just as much as I enjoy looking after him.

Why don't you try offering to cool the jumper out after his ride. That way you'd be riding him when he's only expected to walk. It would give you some time to get comfortable with his size and the very different feel of his stride. Once that's old hat, try warming him up for whoever is going to ride him that day..... Baby steps are good :)
Kathy

Perservere!

It sounds as though your instructors own horse is in a different league to the riding school ponies, which is to be expected. The thing about riding school ponies is they're often chosen for their temperament - the good ones will really look after you and make sure you feel safe with them. Non-riding school horses and ponies will usually try to test you, to see what they can get away with. This is your next challenge - you've learned to ride a horse who's taking care of you, in canter and over jumps, now you get to learn to do all that on a horse who is looking to YOU to take care of HIM. Clearly your instructor thinks you can do it, have faith in yourself.

If it helps, I jumped 4ft at my RS, and have RS horses working round like dressage horses. Now I have a horse on part loan who I don't canter unless I have an instructor there and I'm lucky to get over a 6inch cross pole. But that's ok - its a different type of riding - and I've come a long way in the month I've had him - I can now trot without worrying, I can control his trot, and he's starting to show his trust in me by coming round. In time, I'll get him rounded properly, I'll canter him, and I have no doubt I'll jump 95cm courses, but in the meantime...baby steps.

You need to figure out what it is that you are afriad of, or is making you nervous, or is even making you feel you are incompetent. Afraid of falling? You will have to get over that one dear :) Does it make you uneasy when others watch? Then get a private lesson or do it when less people are at the barn. Is it that he is freaking huge and has a huge gait that is different? Yes, that is quite a difference but it should not make you feel bad. I know this feeling you are describing, it has happened to be before when I got on a 17.1 jumper that was heavy on the forehand and all around scary. You will get used to this horse. Don't be afraid to fall off because we all do and if you can manage to do it with grace when the time comes, you may be able to get up and get back on! Don't be afraid to get off balance at the trot if it's large, or coming out of a fence, because you know that you can just slow down and recollect and get at it again.