You definitely need to take a full course of antibiotics. Don't stop mid course or anything. That's why so many antibiotics are ineffective. And YES antibiotics affect your birth control. Even after you finish your meds, use a barrier method for at least a couple weeks (I'd do a full month, unless pregnancy isn't a big deal for you, which I'm assuming it is
) Dizziness is normal, especially with amoxicillin. If you stay well hydrated and take it on a full stomach it will help mitigate some of that. I hope you get better!!!!