My niece was a picky eater - would actually gag on anything solid. My brother/sister-in-law talked to her doctor who told them not to worry until she was closer to 18 mos, at which point, she should probably see a specialist. In my niece's case, she just grew into a broader spectrum of textures. But, we did give her a cookie, just to test that it wasn't a physical problem. Sure enough, the kid devoured the cookie.
Sounds like you are doing what you can. Try a cookie if you just need a little reassurance.