I have heart palpitations. Is it something to do with my caffeine and nicotine intake?

Hi doctor,

I am 22 years old. I have been having trouble sleeping for almost a year now. Sometimes worse and sometimes better. I am fairly certain it is because of heart palpitations. I am sure it is caused by stress, smoking, or caffeine. So I have been cutting back. And most nights, I can get through it and eventually fall asleep. I have not gone in to do actual tests. Because I have felt like it may be something to do with my caffeine, nicotine intake, and stuff like that, until this point, I was sure I could get better by cutting back, and doing that would help minimize the occurrence of my palpitations. When I first started having palpitations, I would have them during the day, and they were rare and only lasted maybe half a second. I always thought it was just a muscle spasm. I would have them occasionally. But it started happening more frequently, and now it only happens when I am specifically in the transition of falling asleep. As of right now, I have been awake for 48 hours, and I am still skeptical whether it is something I am doing or if it is something more serious. I am worried about going to medical and reporting it because having severe health issues like this almost guarantees a discharge from the navy. But obviously, I know my life is more important. I need to hear a professional opinion from someone before I want to report it. Also, I would like to note that I went to a cardiologist almost a year ago, and he told me my heart was 100% healthy. Please guide me.