Poor academic performance - should/can I apply to a PhD program?

You are now in your mid-thirties. You don't give a precise timeline, but based on your description I'll assume that the poor performance from the first university you attended for your master's happened about 10 years ago. In the meantime, you completed a degree elsewhere with much more distinction, and developed a career and a track record of successful achievements.

The logical conclusion is that any sensible admissions committee will look to your recent record as a much better indicator of your potential to succeed in the graduate program than your more ancient school history. The grades from your old school will very likely be seen as largely irrelevant. So, in my opinion this should not be a major concern.

And as @astronat said in a comment, you'll never know what would happen if you don't try. Good luck!

There is a rule I have for these things: "If you don't apply, the answer is automatically 'No'"

To address some of your concerns:

Transcripts from all institutions attended (*** - insanely difficult and time consuming to get bachelor degree transcripts from university)

Talk to the programs about this requirement - often admissions are written assuming a candidate with a "standard" path through academia, but are more flexible in practice. For example, we recently did some things to help a student coming back after a long period of time because, like in your case, it would be very hard to dig that deep into history.

3 letters of recommendation (** - easy enough, but I feel bad about getting my professors to do this for me if there’s no change of getting it)

There's a chance.

That seems to actually be the core of your question - is there a chance. And I'm going to say the answer to that is yes, despite your difficulties. Now clearly, I can't speak for any particular department's program, but some thoughts:

• Time has passed, you seem to have built a successful and relevant career, and are doing good work. That counts for quite a bit.
• You have a reason. Having undiagnosed ADHD is a perfectly credible explanation for having struggled early in your career, and you have actually demonstrated that this was a turning point. Admissions committees understand that people are human beings.