Hi,
She's feeding and sleeping beautifully you are doing a fab job. I find that if Austin naps in the afternoon after 3pm he doesn't sleep through or won't settle at 7pm. You could encourage her afternoon nap to be earlier closer to a lunctime nap such as 1pm to 2pm (Austin has 12.30 - 14.30). If she is not interested in sleeping at this time you can encourage it by consistently going for a long walk or drive at this time until she has got the gist and falls into that routine.
The other thing I would look at is just trying to up her solids. Sounds as though she is eating great so far so perhaps increase her meal sizes and make sure she has carbs in the evening to get her through - potatoe and leek soup that sort of thing and protein at lunch. It's brilliant that you are home cooking as shop bought is not as filling. To help her take a larger evening meal you could move her lunch forward to 11.30/11.45 then not offer her tea until 5/5:15pm. I know that isn't far off what you are doing but it may help. Also perhaps her milk in the afternoon could be reduced by half, or even less and if you are worried about the milk intake don't forget that 30g of cheese is equal to 7ozs and you can cook with full fat milk and count it as milk intake. Try not to give her milk after 3.15pm or it will put her off taking a big tea. Then offer her some juice or cool boiled water at about /4.30pm to stave off hunger and tO Keep her well hydrated.
Hope that's of some use. Please let me know what you think and how you get on.
Well done though, you are doing a great job. Just fingers crossed you can start getting a bit more sleep soon!
B x x