Thanks for the great trip report MikeH. My first time on Whitney (age 16), I made it to just below Trail Camp before rolling my ankle. Ended up resting at Trail Camp while the rest of my group went up and had a successful summit. Thankfully the rest helped and I was able to get down under my own power.
Second time up (age 17), went with my youth group and ended up descending at the Crest because two members of our group were starting to show signs of AMS - I volunteered to go back down with them and we made it all the way back down to the Portal.
Third time was a charm - just me and a friend (age 20), we made a 4 day trip out of it - sleeping our first night at Outpost, then our second night at Trail Camp - summit on third day - spent the night at Trail Camp again and out on the fourth day.
Just keep tackling it and practice safety first (as you did on this trip) and you should be fine!