Is this normal? - please help!!

I'm 16 and have never masturbated... I have also never been kissed..

I do exercise often and there's something I do (similar to crunches) that makes me feel amazing down there. And sometimes afterwards there's white stuff (like discharge?) in my undies..?

I've never used my fingers or anything down there because I don't know how and it makes me embarrassed even thinking about it to be honest...

Sometimes though I do get the urge to make out with someone and have them on top of me and stuff like that... is that normal?? It's weird for me to even type it 🙈

I don't know anything about this 'stuff' so could someone maybe explain a bit...? 🤷🏼‍♀️😬