Flirtation and serious dating begin and continue very differently. It sounds as if you really aren't aware of this or other body language signals. Everyone likes validation and flirting is a quick fix. I have a long-term flirtation going with a much older woman my wife and I are good friends with. We will NEVER go beyond this. We flirt in front of our respective spouses and other friends, to the point one friend thinks we have an ongoing affair. We never flirt when we're alone. We love our S O's.
If your intention is a flirtation, continues as before.
If you want a sexual relationship with a woman already in a relationship, be very certain of your ability to deal with a jealous boyfriend/husband, including the ability to dodge fists, knives and bullets.
If you want a real adult relationship with a real, unattached, grown ass woman, start asking their relationship status earlier. There should be a quick transition from flirtation to something more grounded.
Note too that you are approaching an age where many if not most women are already in a relationship. A lot who pay any attention to another guy could be seeking an affair. Into their thirties, women are peaking sexually, where men have peaked at around 18. This is just a general guideline, but the likelihood of encountering a woman who is testing the waters of an affair increases a bit. Just be aware.