At 2 weeks it should be a bit bigger that it is, you should be ready to move it into a larger pot. Your soil looks really wet, dont over water. Did you make holes in the bottom of the solo cup for drainage and so air can get to the roots. Is this just a random bag seed are good known genetics? My guess is you are over watering it, let the soil dry out before you water. You should only need to water a solo cup every 2-3 days.