Hi & Welcome
I think the reason you may be having reservations about riding your freshly trained horse is we, (as we get older) realise we are not "bullet-proof" and don't bounce like we used to
at least that is what I am finding as I become a "select" rider. The ground also seems a lot harder, and come to think of it, it's a lot further down too.
Just take your time with him/her, if your trainer did a good job it should not be a problem.
Good luck and be sure to share pictures!