Sounds v stressful!! Poor you, weaning can be soo stressful, can't it! Just remember that milk has loads more calories than any small amounts of solids she would be eating if she was "a good eater", and fats, and all the vits and minerals too.
I'm not sure about supplements, but I'm doing BLW with my 8 month old dd, and I read in the BLW book by Gill Rapely that babies' stores of iron and so on only deplete very gradually, so according to her, we shouldn't worry too much about iron and so on.
FWIW, my dd used to often scream and gag when I fed her pureed food, which made me really anxious (I did purees for a month before I discovered BLW), and when we started BLW she cried a lot when she bit off a bit of food and it was in her mouth and she didn't know what to do with it, and that made me really anxious too. She gagged at the start too, but now she's fine and eats well. She only eats a total of around 2/3 tablespoons of food, which I imagine isn't as important nutritionally as her milk, so I would say don't worry about the nutritional side of solids just now.
If you did decide to do BLW only, at least that would take the pressure off you both for her to actually eat, because you could just leave the decision of whether to eat completely up to her. Your job as mum would just be to give her a variety of food presented in a suitable way, and it would be her job to eat it. Thinking of it that way really helped me. And because she gets all she needs from milk up until she's around one, you could look at meals as sort of "fun food and eating lessons/experiences" rather than a time to fill her tummy. I'm sure you've heard this before, but thinking of it that way really helped me relax about my dd eating v little.
Plus I've heard and read loads of parents say that their los didn't really eat until they were 10 months old or so, and even then, many seem to not eat much a lot of the time after that. I'm sure it must be stressful, but she won't starve herself! She'll get the hang of eating sooner or later! As others have said, you could take her to the doctors as well, just in case.