I don’t know what your doctor means by “just below the borderline” exactly but it sounds like you might benefit from taking a little more allopurinol, if only temporarily.
Your doctor should have been monitoring how your body handles the drug (liver and kidney function especially) and so should know whether you can safely take a higher dose.
Some doctors are slow to tailor the dose to each individual and need their patients to demand it.
There’s no need to make foot baths very hot, just hot enough to get your feet a little reddish and a tiny bit puffy. I think that might be helpful if you tend to have cold feet.
If you also have stiffness or loss of joint mobility due to your bunions, that could also contribute to getting gout symptoms in the feet and you might possibly benefit from gentle exercise or physical therapy. I have for instance very gently used my hands or a towel to forcibly flex a joint a bit more than it would on its own power.
In my experience, arthritis can react quite quickly to one’s last meal. Only I don’t think that’s the purines at work. Food affects the body in many ways.
There is for instance a known link between digesting fat (or is that only some fats?) and the type of inflammation involved in gout. I get reactions from large amounts of egg fat for instance (I’m vegetarian, not vegan). But that’s not the only type of food that gets a reaction from my body. For instance I’ve noticed reactions to salt and some yeasts and/or fermentation products (not just alcohol).
I’m not convinced vegetable purines are all that different by the way. Vegetables simply tend to have much less purines and to boot they tend to pack nutrients that help the body get rid of uric acid. Vegans can have pretty high uric acid anyway, in part because dairy seems to be helpful in limiting uric acid and is generally recommended to people suffering from gout.
You might want to experiment with different types of beans and lentils, not combining them with oil or with eating smaller amounts in any single meal but I’m sorry to say that in my experience milk and yogurt are the safest protein source. Then again I’ve not experimented much with things like quinoa and amaranth so that could possibly be an option. Some vegetables like cauliflower and spinach pack a little useful protein as well.
Hopefully in a few months’ time you won’t get attacks any more and you’ll be able to forget about trigger foods.
Finally, this might seem obvious but I don’t know what drugs you’ve tried: some drugs which do not cure gout are nevertheless very useful to deal with gout symptoms, either to prevent attacks or to suppress them before they bloom. Some of us have taken quite the cocktail to deal with attacks.