You might try two things, just as ideas -- even just try it on a few and see if it changes responses any. Or send these to people who never got back to you the first time.
1. In your cover letter quickly describe one/two thing(s) that you have done that is relevant and might open a dialog for further discussion. Or peak someones interest at least.
2. Try reformatting your resume to be less about chronological order and more about skill set and tasks you have done. Use bullet points for libraries, API's etc to help bulk it up and make it obvious what you have worked with. Just don't ever lie.
Option #2 is what people with only a little or people with a lot of experience generally use because chronology puts an age on our head. Personally, I have seen that many people immediately calculate my age after seeing that I have been in industry for quite a while. Sometimes it is funny to watch/hear, other times it is just sad as you literally can watch their attitude flip, same goes for when you are young too. It is just human nature to some degree.
