Hello, and welcome.
I'm sorry you're not seeing your Trusted Traveler or (KTN--Known Traveler Number) on your current boarding pass. This is not an uncommon occurrence. TSA Pre passengers are not guaranteed to be selected for their boarding pass to show their KTN on every flight. This is a randomized selection system which enhances security measures.
However, because of your age and if you have any medical conditions or find it hard to stand for a long time, on the security screening line, you can ask 'TSA Cares' for help. You're supposed to let them know 72 hours in advance, that you will be needing help, but under the circumstances, they should understand and help you with a wheelchair and/or to get through the security screening line more quickly.
Here is the phone number and hours for TSA Cares and Passenger Support:
Email TSA Cares
Federal Relay: 711
8 a.m. to 11 p.m. ET
9 a.m. to 8 p.m. ET
I hope this helped and you have a wonderful flight!
I hope you found this answer helpful and will please take a moment to select a positive rating from the ratings box at the top of your page, then click 'submit;' this is the only way I will receive credit for assisting you. Thank you very much!
Even after rating, I will always be available if you need additional information; just click 'reply' and I will be glad to continue.