Yes having a trainer is invaluable. Taking video of ones-self while riding is also a valuable tool. It is also a great thing to have another person take video of you while being instructed by your trainer.
When you watch the video you can listen to the instruction and see what happens with the horse and yourself as you put into action the trainer/instructors direction.
To the OP.
Do you have pictures and/or video of your horse??? That would be good if you could post it!