Getting on-site means you're at least better for the position that the ones who weren't invited on-site, so that's a start. And you definitely don't need a CE/

Getting on-site means you're at least better for the position that the ones who weren't invited on-site, so that's a start. And you definitely don't need a CE/EE Bachelor's to be a good programmer - especially since it sounds like you're not completely green (having at least done freelance development work and, more importantly, being paid for it!). Do your best to present yourself as humbly confident in the interview. Good luck :)