apologies, as my situation is similar on the face of it but completely different for every single variable you mentioned, but to throw it in:
I was longer-term on SNRIs before an ADHD diagnosis (like absolutely confirmed, i've never passed a test so convincingly lmao) and starting Ritalin gave me a marked improvement to the point that I put off an imminent dosage increase of my desvenlafaxine (because my ADHD symptoms were being addressed).
I'm going to leave it to others who are more experienced with your combination and more versed in the literature, but if you want the anecdotal opinion of a random nerd who will be thinking about this all day: the two-pronged approach helped me immensely personally, and I would assume much more so than a simple increase of one or the other. Antidepressants though are always an inexact science, and I definitely don't mean that in a crank way, but I mean that the prescription is issued to deal with how we feel - and even when we don't know how we feel, no one else can know because there's no blood tests or scans or whatever. So you'll just have to monitor and be honest with yourself and your doctor when thinking about how much it's helped, if anything is making you feel worse, and if the combination is suddenly making you concerned about any symptoms or issues. If it feels wrong, it's wrong.