So it's not really worsened in a year and you've only been taking treatment for the last 2 days? That's a strange case. Your pictures definitely look like your balding at the sides.
I was worried initially about the side effects too and stuck to minoxidil, but I've been on finasteride for 6 months now no...
I'm 21, and I've been losing my hair gradually since I was 18. I started using Minoxidil (Minoxidil Max: 15% Minoxidil and 5% Azelaic Acid) for over a year, noticed okay results but nothing spectacular, and so 6 months ago I started on finasteride (again, the Minoxidil Max brand but now with 15%...
If you're 17 then you have aggressive male pattern baldness, so I would stay with finasteride if you want to prevent further balding. Minoxidil is simply a growth stimulant. You'll want to use both if you can, so keep using finasteride unless you notice any side effects. Oh, I'd definitely go for foam if possible...