ok she is only 2.5 this can be a fussy age, you say you have tried everything, well STOP, just make mealtimes a normal not event, sit down to eat togther give her a SMALL portion of whatever she is having then you and your ds and dh? sit and eat, if she eats great if not NO COMMENT, at the end of the meal take away her plate end off! if she eats, say 'thankyou for sitting and eating nicely' or something simple like that, do the same to ds.
try and involve her in shopping ,food prep and cooking where you can.
at this age she will still need snacks before meals, i would keep them simple and not within an hour before a meal time unless you have to.
you need to relax a bit, she wont starve herself, get her checked by hv/gp if you are worried, but take the stress out of mealtimes, dont let it become a battle if she eats it great, if not no big deal, but nothing else after dinner, does she have milk before bed? that would be my exception.
i remember one great hv saying to me your job is to provide a healthy balanced diet, it is NOT your job to make them eat it, only they can do that so once you have provided food you have done your bit!
btw with the SMALL portion if she eats it all and asks for more then thats great, i often find that works better, they can be daunted by big servings so just small amounts but they can have extra if they want to, again putting them in control a bit.
anway that has always been our take on mealtimes, we all sit andfood is there, we chat and have a nice mealtime but if they dont eat, they dont eat and its ignored/simply not commented on other than a 'never mind maybe you will feel more like eating another time' or simply 'are you all done? i will take your plate away then'
its REALLY hard not to get wound up, resort to bribery etc but i dont find any of that helps.