Yeah so if she doesn't eat I do tend to give her an alternative
Ok so no toddler is going to try any new food if they refuse it knowing that a more preferred food will magically appear. Well maybe some rare toddlers would but your DD doesn't seem to fit into that rare club. I'd definitely stop offering alternatives and if she doesn't eat, just assume she's not hungry and clear away. It might take her a short while to adjust and she may protest but hold firm OP and she'll understand.
I don't eat at the table with her maybe I will try that?
I'd try abc eat with her and not be too concerned about what she does and doesn't eat.
There are some great family recipes on BBC Food and Taming Twinss* has some excellent ones too.
And maybe constantly put stuff on her plate that is new. I just feel she always eats the preferred food and never touches the other stuff. EVER.
I would still put the new food on her plate but put a small amount of a food you know she will eat alongside it. Don't encourage it cajole her to try anything, pretty much blithely ignore any protests. We always had the rule from a young age that you don't have to eat any food, but it stays in your plate. Sometimes they'd pick it up and try it, sometimes they wouldn't but they always had a little of something on there that they would eat.
Is she getting plenty of exercise too? I found mine were always more willing to eat everything if they had done things like Bern to playgroup, swimming or just toddled around the park for a while.