Kate false negatives can be reasonably common but false positives are almost never heard of (that's what the doc told my teenage sister when we went to the docs imploring her to tell us that the preg test sis tok earlier was wrong... the result of that test is a gorgeous 8yo).
Good on you for going to the md on Monday but IMO you're definitely pregnant and it's time to start looking at different wedding dresses (or moving the whole affair forward so you can fit your dress).