Girl you're never too old to follow your dreams and while there could possibly be some limitations as to the amount of feminization you will achieve on HRT, I wouldn't let that get in the way.
I started my transition 15 months ago at the age of 51 and never gave a second thought to my age. For a lot of us TG girls, it takes this long to finally build the courage, or frustration, to act on something we have felt and known our entire lives.
So let your heart lead you and do what you feel is best for you. You only get one go at it in this world so make the most of it!