The article you saw was mistaken: Having regular sex doesn’t affect hormone production. At 55, you’re still within the range of “normal” for reaching natural menopause, which is defined as a year without menstruation. While the average is 52, the actual age is generally from 40 to 60.
What is true is that having regular sex will counter one of the most common results of menopause, which is vaginal dryness and painful intercourse. Having intercourse increases blood circulation, which keeps tissues healthy. That’s where the “use it or lose it” adage comes from: Maintaining blood supply can delay the onset of these symptoms, and lessen their severity as hormone levels continue to decline.
I’m glad you and your partner are sharing regular intimacy! And be aware there’s some research suggesting benefits from late menopause.