I haven't personally used the Paragard, but I wanted to say something about your current birth control method.

It is very possible to get pregnant from pre-cum. Sperm, even from pre-cum, can live inside of you for up to five days. Because you are very young and probably very fertile, I would highly recommend, until you are either using Paragard or hormonal birth control, you use condoms EVERY time you have sex. It isn't that hard to find stories about someone who thought their cycle was 100% accurate all the time and used FAM as birth control and they ended up pregnant.

Other than that, some of my friends have GAD and use hormonal birth control and don't experience any additional symptoms or the HBC even makes their GAD better because their hormones don't fluctuate as much. I understand where you're coming from being concerned about HBC messing up your emotions, a type of birth control I was on made me depressed, but HBC shouldn't do that - and if it does, it isn't the right BC for you. That's why I like birth controls I can stop using immediately if I feel that something is wrong.

Honestly, I would talk to your doctor about your concerns, tell them what you want out of your birth control (i.e. don't want to worry about taking a pill every day, don't want hormones, want localized hormones, want your periods shorter, don't want periods, etc), and see what they suggest. Your body is different from everyone else's body and just because something worked for a stranger on the internet, doesn't mean it'll work for you.