If I am reading your story right, the horse bucked you off once, then you were grounded for awhile but did lots of groundwork. Finally you got on again, and he bucked you off again.
If you are getting along well doing ground work, I am guessing the issue is either that the saddle doesn't fit, or that the horse is not well trained to being ridden.
From what you say, I would consider the possibility that the horse is not trained to be ridden yet, because packing and ground work will not train a horse to be ridden. Do you know for sure the trainer that worked with the horse actually spent time riding him?
Another thing to consider is that a horse "green broke" to being ridden needs some experience and miles before you can expect to get on after a period of time and be certain he won't buck. Anything that scares or feels "off" to a green horse might cause bucking. Even if the last time you rode in November made the horse scared somehow, it might have caused him to buck this time just remembering that experience.
Usually I am ready for a buck to happen anytime in the first 100 rides.
Something not everyone realizes is that training for riding must happen during riding. You can do years of groundwork and the horse will still be completely green to riding until he has some experience doing it.
My suggestion is to not get on the horse yourself, but instead enlist the help of an experienced rider. That person can evaluate the horse and discover why he is bucking, and also get him through the first several rides. Ideally, if you don't want to get bucked off again I'd have someone do the first 60-100 rides for you. I've seen some trainers that spend 30 days with a horse but only ride three times before sending the horse to the new owner. That horse is still extremely green and there is a good chance they still might buck at some point.
People who are experienced with getting bucked off will often test the horse a bit before committing to getting completely on - if they suspect a horse might buck. I usually hop up and down in the stirrup a few times to make sure the horse seems calm and also wiggle the saddle and slap the stirrups around, making lots of noise. I stand on something taller than the horse and wave my arms, seeing if this makes him react. Then I lay on my stomach so I can just slide off if the horse rushes off or starts bucking. If the horse is calm with all of this, then I will commit to sitting in the saddle. It also saves you from discovering the saddle is causing back pain when you are on the horse. If the back hurts or the saddle pinches, the horse will usually react to your weight just hanging over the saddle or pressing down in the stirrup.
Last edited by gottatrot; 02-01-2017 at 05:43 AM.