I sanded the brake pads today and braking is way better than before. I also cleaned the rims and pads with some cleaner. The pads felt slippery before I sanded them but a couple seconds of sanding with 220 grit sand paper made them feel like new again. Thanks for the help guys!

And I am gonna stay away from sanding my rims right now, but if I upgrade rims later I will sand my current ones and see if the braking is improved.