After a prostatectomy, you’re supposed to get salvage radiation when your PSA hits .2. That’s what happened to me. 3 1/2 years after my prostatectomy, my PSA started rising when it put .2 they gave me a looper shot and two months Later I had 40 sessions of salvage radiation.

You have waited longer than you should have. You need a PSMA PET scan to see if the cancer has spread somewhere outside the prostate. Ask your doctor about this they should be already planning on this.

Here is with the American Society of clinical oncology has to say about getting Treated when your PSA goes up after a prostatectomy. This is something else you need to discuss with your doctor. Why have plans not already been set.

From Ascopubs about what PSA to do salvage radiation.
≤0.2 ng/mL:
Starting at this level maximizes disease control and long-term survival. Patients treated at PSA < 0.2 ng/mL achieve higher rates of undetectable post-SRT PSA (56-70%) and improved 5-year progression-free survival (62.7-75%).
Delaying SRT beyond PSA ≥0.25 ng/mL increases mortality risk by ~50%.
0.2–0.5 ng/mL:
Still effective, particularly for patients with low-risk features (e.g., Gleason ≤7, slow PSA doubling time). The Journal of Clinical Oncology recommends SRT before PSA exceeds 0.25 ng/mL to preserve curative potential.
0.5–1.0 ng/mL:
Salvage radiation remains beneficial but may require combining with androgen deprivation therapy (ADT) for higher-risk cases.

This article discusses the above;
https://ascopost.com/news/march-2023/psa-level-at-time-of-salvage-radiation-therapy-after-radical-prostatectomy-and-risk-of-all-cause-mortality/