I would suggest trying not to put so much pressure on yourself and the little one at meal time. Our job is to provide them a healthy variety of foods, and their job is to decide how much or little to eat. If she doesn't want dinner that's fine as long as she's reaching growth expectations. My four year old regularly refuses to eat dinner but eats well at other meals/snack times. I make sure she knows there won't be any food offered after dinner. (bedtime is about an hour after dinner).
If she been eating something more oftenthat she likes or tastes better, she going to eat that or want it maybe. Or maybe is being seated and constrained for long periods and not wantto sit and eat cause she not hungry...
Wow, that sounds really hard. Have you varied her food as she grew up or do you tend to give her the same things? My daughter stopped eating avocados but now if I make it into guacamole by adding spices and some salsa she will eat the whole thing. I also try to give different textures at each meal ie. One smoothie, one hummus w small chunks of cucumber, then a bigger hand held item like celery w pb on it. That way if she isn't feeling it I move on. I also don't give her everything at once. Could overwhelm them. Another question is she feeding herself or are you trying to feed her?