If you came to the fence in a solid CC form, I don't know - I'd have to see the pics or vids.
If your coach blames your horse - then I'd question my coach.
I cliniqued under Ian Millar eons ago through Pony Club - and he said something that will always stick with me till the day I die.
"I good rider conforms to their horse and a poor rider makes their horse conform to them. A good rider blames themselves for erros, and a poor rider blames their horse"