I'd say, forget about your age. The fact that you are worried about it, creates difficulties that you don't need ... Just keep on working and see what will happen.
Being an adult beginner has a lot of advantages. As an adult you are mature, you have (hopefully) overcome all the agonies from adolescence and growing up to be independent. You have life experience, you have 8hopefully) learned how to learn, you can work methodically and with a perspective. And HOPEFULLY you don't feel you have to "prove" your qualities all the time, you know you have a worth as a human even though you have your bad days at the piano.
Being an adult beginner also has some disadvantages. No, it is not about "stiff neural synapses" and all that nonsense, it is not like a window is shut with a boom when you reach the "mature" age of 14 and suddenly you cannot learn anything properly - it might be true when it comes to learning languages, it seems that adult learners have a hard time getting rid of their foreign accent when they speak. It might be true when it comes to olympic gymnastics. But piano playing is neither, so don't worry. But keep in mind that adults sometimes tend to be rather ... stubborn. They often question every new idea, they almost automatically activate some resistance when the teacher has opinions that differ from their own. (Yeah yeah, I am also an adult!) "You think so? No ... I am not sure you are right here ..." I think young students better have the ability to absorb new knowledge with a more open mind, because being critical is a part of the human development.
So, I'd say it is not about age at all, but about attitude. Which, on the other hand, is good news. Your age, measured as loops around the sun, is something you cannot affect. Your attitude, however, is something you can always work with. I think that if you are prepared to be very humble, very open-minded, yet also very methodical and not haunted by some disbeliefs about "age limits", you can achieve just about anything you like. And, as always, you also have to realize that there is a price to pay, and it's you who decide if you like to pay or not.
I am also a rebounder, I will be 50 next year. I took lessons during my teen years. Even though I got some acknowledgement from my teacher, I was rather lazy and rather occupied by other stuff, so I never got very far. The most difficult piece I ever played was Clair de Lune. Then I went to the university, and from there I went on with job career, partner, children ... the usual stuff. My piano playing was practically in hibernation for nearly three decades. Sometimes I made desperate efforts to play again, but I was always disappointed and frustrated to notice that I was so bad.
Just a few years ago I decided to go serious again, though. And I did. I almost had to start from scratch again, and I think it took more than a year before I even was up to my former "top level" ... I also had to fight some muscular injuries, caused by bad technique and too much enthusiasm, an perhaps also a body which was not 20 anymore. (I seem to be predisposed to muscular and joint issues, it obviously runs in my family

)
Well, now it has been three more years and now I have surpassed my former lever by far, and I learn pieces I could not even DREAM of learning before. Why? Because I have learned to practice effectively, I have clear ideas on how the music should sound and I know what I'm doing - at least much better than in my younger years. And most of all, I have realized that practicing is not just about sitting at the piano and trying to press as many keys as possible every day.
Practicing, to me, could be about sitting in an armchair and read the notes. It could be about walking the dogs and at the same time plan my next practicing session, or that particular bar in that Beethoven sonata that is ringing in my head. Or about listening to other pianists. There are periods when I do not have much time to practice because I am self employed and I have many issues concerning my family and my private life. OK, so the piano has to wait. And then I am back and keep on working. I have no idea what "grade" I am at and frankly I don't care either, I have no idea "what to do" with this hobby of mine. What I know, is that I love this music and I love to create it with my own hands, and I think it is fun to learn new pieces and take on new challenges.
I do technical exercises when I think they are called for, but otherwise I skip them. My lodestars are "motivation" and "mindful practice". I believe it is harmful to practice mindlessly, to work through this and that many exercises just for the sake of it - if you do an exercise, or a scale, then you must pay full attention to WHAT you are doing, and WHY you are doing it. It is not llike aerobics when you can do your daily 20 push-ups or your daily run around the block while your mind is somewhere else, and you still get the full benefit of your efforts.
The classical advice from Liszt was: "think ten times, play once". I believe he was very right.