Casual dating with a younger girl?

Oh boy i have a feeling im gonna hear it from all of you but this is my situation and i need help, be aware you are about to see a million red flags so im begging your not to harsh and provide something constructive. I have been working with this 19 year old girl at my work. Since day one i have had a small crush on her but never thought to act on it due to lack of knowing anything about her and her being so young. Well somewhere down the road we started talking and had an instant connection. Feelings that i have not felt in a long time. She professed to have the same feeling but asked to keep things casual and avoid rushing into things, also She plays the im 19 card and i have the right to act like a fool for another year. Things started moving rather fast, with her staying here every night, sleeping with her, spending every day with her it started to feel more like a relationship. this is where things turn sour because she tells me that she still has a sweet spot for her ex but cant bare to lose me from her life. Now its like i placed her under a microscope and slowly started to notice all the times she was texting him when we were together and when we were not. I took all this to heart and backed out thinking if she was still hooked on him my chances of this being bullet proof where slim to none. To my surprise she came back and begged to make this work, being a gluten for punishment it seems i took her back, but now i felt the trust was beginning to dwindle away. After a few more break offs of this casual dating situation we are back to the basics. Shes saying that all the feelings are there, along with the attraction but she wants to keep it chill and casual until shes ready to move into something more serious. Im lost, im old school, i feel like if its there then be together if its not then dint. I dont know what to do with this or how to handle it. Shes worth all the effort i can provide as long as its productive and has a end result worth working towards. Otherwise i can and will cut my loses and move on. What do i do to keep this working in my favor with out freaking out because shes slow to commit.