First time overthinking!! In need of advice please

Hi there!! I’m truly in need of some desperate advice or even personal experiences. All would be very very much appreciated.

3 days ago (Mon. The 15th) my partner and I had sex for the first time. Protected sex using a condom he ejaculated inside me and I guess it’s all the outside speculating and overthinking but I was considering taking the pill but I’m incredibly nervous hearing all the side effects.

Ik every woman is different but I have a few questions hoping to put my nerves at ease.

1. When should I begin taking the pills (I got them from Planned Parenthood today.. Thursday the 18th) and my period starts on the 30th and I have a pretty regular cycle. I was told I can take it on Sunday but I’m hearing it’s better to result in a more natural cycle to take it on the Sunday after your period.

2. I truly am not incredibly sexually active but I thought better safe then sorry. But is it worth taking with all these side effects in my case anyway? I hear there are many other benefits such as helping with acne but I don’t have any and regulating your cycle but again..my cycle is pretty regular.

3. And if I were to stop taking them, could there be further side effects.

Again any advice is helpful my nerves are skyrocketing so please no negativity. Thank you have a blessed day!❤️