Difficult decision ahead

If they believe they know its full extent and its small and away from the edge of the prostate It's likely you could keep monitoring it.  A stable psa is usually a good indicator.

If it appears to be close to the edge you might want to be more cautious.

There might be other options to Radiotherapy and Surgery.   Brachytherapy or other more exotic treatments.  Although it depends what your hospital offers and how far you're willing to travel if they say you'll need to go elsewhere.

Your psa is very low and in by far the most cases that's a good sign.  Although there are cases where psa doesn't increase as much as you'd think.  The doctor should know roughly how large the lesion is, mine was said to be 13mm which isn't large but is getting that way, it isn't small.  I'd imagine yours is about 5mm but that's pure guesswork and if you have an enlarged prostate it makes it relatively smaller.

From how I feel now I think I'd be going for AS in your shoes.  But puttnig it into perspective how long do you think you're putting off the inevitable and are you able to have a less aggressive treatment now, e.g. Brachytherapy, than if you wait.

All the best
Peter

As Cheshire Chris said, you're probably in possession of (or be able to ask for) a bit more information than you've posted which might help make up your mind.

But on the face of it, given your age and circumstances and presuming there was only a small amount of biopsy cores positive combined with the low PSA and Gleason score, there's definitely a good argument for active surveillance I would say.

Bear in mind though that staying on active surveillance should involve regular PSA tests (every 6 months) and MRI scans (every year). If your PSA starts to rise steadily and/or the scans change, then you'll need to have further biopsies.

The tool/website linked below, is based on the findings of a large scale clinical study - it's obviously not definitive but I found it useful. It gives an indication of the difference in outcomes/survival rates between choosing to go down the active surveillance (conservative) route vs the radical intervention route. I think if you enter your numbers, the difference in outcomes for your staging will be very, very marginal.

https://prostate.predict.nhs.uk/tool

All the standard treatments apparently give about the same success rate in eliminating the cancer, but differ in the likelihood of short-term and long-term side effects (which anyway vary between individuals and you have no way of knowing what they will be for you). Most likely opting for AS will just delay the treatment decision for an unknown period, but with your caring responsibilities that might be the best as long as your psychology can carry the knowledge you have a cancer that could progress.

And in some ways, if you do wait until PSA rises the treatment decision may get easier. Surgery leaves you very dependent on others' support in the short term and recovery times favour younger ages, while radiotherapy is less traumatic short term (though not to be under-estimated, it drains you of energy) and your perspective on long term side effects may change if you don't need the procedure until you are already in your late seventies.