If you are stretching properly, you shouldn't need tapers.
Tapers are not jewelry, and shouldn't be worn as jewelry. You shouldn't be wearing them at all.
You cannot skip sizes. I doubt you have been stretching properly, so if you do jump from 14g to a 10g, you will most likely get a blowout and have to stop stretching completely.
First, get the right jewelry for your ears. Get implant grade materials, and get plugs or tunnels. Tapers are not needed if you are stretching properly, your ear should be relaxed enough to accept the new jewelry. If it hurts, you aren't ready to size up.
Once you have the right jewelry in your ears, you can start getting the smaller one caught up. You might be able to get a 12g in there, but don't force it, you don't want a blowout. If it hurts, stop.
You need to wait a minimum of 6 weeks between each size up. This lets the inside of the ear heal and get ready for the next stretch.