Hi Nick,
I read your profile, it sounds like you're having a stressful time.
I've made a summary of it to try to help anyone who may comment. Your psa went down to 0.01 after surgery, which was last September, but not undetectable. There was an element removed that they hadn't seen on scans and it was close to the bladder leaving a positive margin. Your psa is now 0.17 after being 0.06 in February. Your psma scan is in 6 weeks so mid-August after which HT, RT and more HT are anticipated.
Your psa could have reached a level where a scan is more likely to find something in 6 weeks. I'd be thinking it was in the area where they left a positive margin.
As your father has it and you're youngish you should be getting priority.
You've had quite a few delays, I'd try to keep them to the time said and make the case of your age and father. Wishing you strength and all the best, Peter