It is something to do with your image content because G can't read images so if possible write the content and make the font downloadable so that people can read it as well. Yes, domain name does help to increase your traffic and thus your earnings. Try different combinations of Ad Typs, Link units, color schemes and use channels to track the performance. It is hard work my friend and experimentation.
With 35 visitors a day, you earn $23 in 6 months? That's almost $4/month and that's around $0.13/day? You need to increase your traffic