Are you being treated by a real cancer specialist, a medical oncologist? If so, does (s)he have extensive experience with PCa?
Your 0.02 PSA is excellent; fits the definition of "undetectable."
According to one of the leading specialists in PCa, med onc Stephen B. Strum, MD, a patient should have an undetectable PSA for at least one year on treatment before considering a suspension. It's called IADT (Intermittent Androgen Deprivation Therapy).
When the PSA begins (probably but not certainly) rising again, the ADT is restarted. The "off" time varies.
(1) was surgery prescribed for you when you had known mets at C3, T6, L iliac crest, and R acetabulum?
(2) what was your Gleason score at dx?
(3) what was your PSA at dx?
As above, it is possible that PSA might not rise again, but don't bet your life on it.
ANECDOTE alert: I can, with fear and trembling, give you this personal experience. DO NOT rely upon my story to make any treatment decisions! What helps me may harm you, and vice versa.
I have been on a regimen of IADT for about four years. I have used Trelstar (similar to Lupron), plus Avodart, staying on Avodart during "off" periods. Inevitably, PSA rises because this is not a curative treatment; there is no such thing at this stage. It's called a "vacation" because testosterone recovers (yee-haw!).
Some add Casodex/bicalutimide to the mix, (ADT3).
When PSA (I have a 28-day testing cycle) rises to my trigger point, I restart the ADT.
At some point, the ADT might cease to be effective. That's when the patient educates himself, consults with his oncologist, tries to propitiate his gods, and selects the next treatment.
There is a great deal to learn, and I strongly recommend the following sources of reliable and unbiased information:
(a) The authoritative website of the Prostate Cancer Research Institute (PCRI) at http://www.prostate-cancer.org/pcricms/
(b) _A Primer on Prostate Cancer_ 2nd ed., subtitled "The Empowered Patient's Guide" by medical oncologist and PCa specialist Stephen B. Strum, MD and PCa warrior Donna Pogliano. It is available from the PCRI website and the like, as well as Amazon (30+ five-star reviews), Barnes & Noble, and bookstores. A lifesaver, as I very well know.