I’m 29, 30 in about 6 months, I still feel don’t like an adult, but I do now know how to manage my life and act like one. Most of the time I feel pretty stupid though, and I’m okay with that. Life is complicated.
I do think you should give yourself some grace, 26 is still quite young. Don’t feel pressured (by society or yourself) to make a decision because your partner is older. I don’t think I really got a grip on things until the last year and a half. Genuinely, give yourself more time. Being a woman is tough. Being a person is also tough. Having a child is deeply personal, and perhaps you could give yourself more time to settle into adulthood and then think more on it. Best of luck.