You haven't mentioned what software it is. If it is doing "auto kerning" and you can't turn that off, then it doesn't sound like any change to the font will help, since any added bearings in the font will probably be cancelled out again by the software. So your first priority would be to try and get whatever software it is, to try and disable that feature or adjust your "tracking" or "letter spacing".
FontForge (free font editor) allows you to adjust the width of letter spacing in a font by selecting all desired characters, going to "Metrics" -> "Set Width" -> "Increment width by..." but it may not be as simple as that (it may affect placement of combining accents?). I guess it's a route for experimentation.