Hi Louise, I'm glad you liked my blog!  Please feel free to read all of my blogs and ask any questions.

Be careful of your back.  Start SLOW.  Don't try to "push past the pain", that is for young fools who do not know how much they will hurt when they get older.  There is nothing wrong with just walking until your back does not hurt.  Until your back stops hurting I'd put off the sitting trot unless you are lucky enough to ride a REALLY smooth horse.  This may interfere with dressage lessons, sitting trot is basic for them.  You are only 44, get back so riding is fun and does not hurt THEN you will be fit and loose enough to learn dressage.

A lot of people don't agree with me of course.  I could not ride for 3-4 years because it hurt my back too much after a car wreck.  Finally, in desperation, I decided to crawl like a baby (hand weeding my horse's grazing paddock) and after several months or so of that my back started working properly again.  You are only 44, you have plenty of riding years ahead of you.  It never hurts to start slowly, improvement WILL come!