I've developed a new anxiety around my heartbeat and have started checking it. The anxiety really started after I had heart palpitations of 120 bpm for an hour one night, not triggered by anxiety but it lead to severe anxiety. Hasnt happened since but I've been checking my heart rate more and am disturbed by how much my resting heart rate varies. 
Sometimes it's 60, 75, 90 or 100 like right now. I never used to check my heart rate so I don't know how normal it is to have a fluctuating resting heart rate but it is scaring me that I have heart problems.

I know your heart rate varies throughout the day depending on what you're doing but I don't know that it's normal for resting heart rate to vary?

Also the other day I was walking up a non steep hill and it reached 192 bpm, only 1 beat less than my maximum safe heart rate for exercise. Is it even safe or normal to be this unfit? I'm a slim 27 year old woman.

If anyone has experienced these things I'd be grateful to know so that I don't feel alone or like I have a heart condition or something terrifying