I don't know what to do

I have been clean now for about 3 months now. I have smoked for about 2 years since I was 15 when started.

It was All I had. To keep me calm and stop myself from overthinking. Recently I have been starting to over-think more and more each night. Which has kept me up till 3am. I promised to quit for a girl who cares bout me and who I like and knows that I have feelings for her. Basically I over think bout what she said when I told her I liked her and some other family matters. I feel like I'm addicted to the short term calm I get from smoking and not the nicotine. I don't know what to do anymore.