Thank you all so much, I feel a lot better reading your comments. I am definitely getting stressed out with it all and I'm sure she is picking up on it, creating a cycle. A more relaxed approach sounds sensible.
Is she eating anything, is her poop like proper poop (sorry!)
I think she is eating something occasionally, as from time to time there is the odd identifiable piece of carrot or broccoli in there!
Does she have any favourites?
Not really, she doesn't seem to dislike any particular food but just gets in a general worked up state. When she first tastes things she usually seems happy enough, so it's odd really
Could this be a teething pain thing?
Possibly!
Has she got a variety of finger food to taste?
If I'm honest, I get very anxious about finger foods and choking 
So I offer more spoon food. She usually grabs the spoon off me and smears it everywhere though...
I want to offer more finger food, I need to get a bit braver.
Can she see her playmat when eating, is she more pro-toy not anti-food?
No she is in a different room, but she gets very distracted (eg she spends a lot more time chewing her bib than showing any interest in the actual food!
Offering finger food on the play mat could be a plan, but again I am so worried about choking and the mess
What would be the best things to give her in a more casual environment?