Have you tried the TV. I know this goes against so many perfect parent principles but we found it very effective during the fussy stages. When DS1 was older we stopped TV during meals (and this is now non negotiable, he is 4) but by this time he had learned that sitting to eat was the way things are done in our house.
I found it difficult to get him to eat 'with' the family at this age and as such fed him before. But gradually introduced him to the family dinner table as he improved.

If you're ok with it, it is more 'natural' for toddlers to snack and walk around etc, sitting still to eat a full meal doesn't come naturally. But for us we insisted on sitting to eat (and still do), especially at breakfast and dinner time. It really depends on what you're comfortable with and the way you wish to parent. Best of luck.