It probably means some cancer was left behind, which you knew anyway because of the positive surgical margin. You may want to read the following that address situations like yours:When should the patient and doctor consider salvage radiation therapy?
But that only tells you that your PSA is likely to keep rising. What it doesn't address is whether your cancer needs to be treated. Especially with your pathology GS 6 (I assume that was from your pathology report and not your biopsy), it is very unlikely that it will progress and metastasize anytime soon, and possibly not in your lifetime. You may well be in that category of men who have been on active surveillance for 20 years and have never needed treatment. So one option is to go on a kind of active surveillance and monitor your PSA.
Another option is to get a Decipher test, which may allow you to rule out that your kind of cancer has metastatic potential. That test costs around $4000. Medicare and some insurance may cover it - check first. Here's some info about
it:Genomic classifier can help identify patients who may not need adjuvant radiation
Your other option is to go ahead and have adjuvant radiation. It is certainly more curative to do it sooner rather than later, but whether or not it actually saves lives, especially in a case like yours, is controversial. Only you can decide if that risk is reasonable to you, or if you prefer to wait in order to avoid the SEs of salvage radiation.
At any rate, you should be talking to a radiation oncologist.