Okay, I'm 30 and I've been doing PUA for the past 5 years. I've dated women anywhere from 18 to 35 in my time doing this so I have some experience in this department.
First off, she likes you a lot. Her display of telling you she wouldn't date someone else without telling you and coming down on you about it is just her way of telling you she likes you. Furthermore, she gave another huge indicator cause she wanted to see you Sunday too. This girl really likes you a lot and there isn't a huge age difference in 25 and 27 or in maturity for the most part.
There is a common misconception around men that older women want older guys. Well, back in high school & college a lot of women who were 18-23 wanted older guys cause of stability and success in their personal lives. It seems that you definitely have that. Women who are in their mid 20s are looking for someone in their age range who is independent, has a good job, car, their own place, and someone that they like being around...and that's about it.
I can understand the way you feel and I've felt that way many times myself when I started dating older women. But the truth is they can be perfectly content with you. So please break that limiting belief now that because of your age she's always going to be looking for someone older. That simply isn't the case.
You could very well be someone she sees for long term potential which again based on your descriptions of interactions with her I believe she does. She is just wanting to take things slow because of her past rocky relationships, and she wants to enjoy being around you.
She sounds like a great catch bro. I would really put my time and effort into seeing her as much as you can and develop your new relationship with her.
Jon