I feel like a creep

I go to the gym and I met this amazing girl who's only 19 and we clicked instantly. We had a gym date together for 3 hours, went for coffee after and I dropped her off home and even said hi to her mother ( who was waiting outside ).

We scheduled a date in the city next weekend as a proper date and she keeps texting we hearts and emojis and all types of gifs. I just realized that I'm half way to 29, almost 30 and she's only 19. I really like her and want to go on our date but something keeps bothering me, making me want to end this. I feel terrible and am at a loss on what do.

She knows my age from the 2nd time we talked at the gym. She even joked that I " look good for a grandpa hihi ".