Hi Kimi, welcome to Susan's
As long as your heart, blood pressure, liver, lungs, blood checks out OK you can be 99 years old, if you pass the physical you can transition and have SRS as well. I am sixty four, been living full time 9 years and post-op 4 years. There is another here who is 73 years old and had her surgery at the age I am now.
Aging will affect you in the sense that as you get older you're testosterone level drops as a normal result of aging. With the lower testosterone level you will find an acceleration in your gender dysphoria complication and discover it being increasingly more dificult to control or repress effectively as a result.
It is said that HRT works most effectively the younger you are, and I will not dispute that, for it appears to be a more constant result in the younger generation. then it does in the older generation. But I am quite satisfied with what I got out of the estrogen in the past 9 years, I have no complaints, it may just take a little longer then a younger person. I am the one with the long brown hair on the right in my avatar pic and that is my partner sitting tot the left of me.
When your time comes that you need to go forward hun, just put one foot ahead of the other and don't look back. Because in the end it is your decision to make and only yours, on one else, you do it for you. Of course do consult a therapist to help walk you through it, you will need someone who is a professional to confide in.
Cindy