I feel like this is where I need to do some shameless self promotion, as we have been growing and selling heritage Red Fife wheat grain and flour for a few years now...if anyone is ever in need. We are always happy to send grain via CP for the cost of shipping.
As for advice, you have to feel it to tell if you're grinding it fine enough. There's a point at which the flour stops feeling sandy and starts feeling like fine clay where you can tell it's a better grind. This last bit is personal, but Anna and I feel like the flour bakes better bread and is probably even better for your health if you sift out most of the bran with a kitchen sieve. It's always difficult to navigate the myriad of different views on nutrition out there, but there is evidence that bran is the most difficult part of the grain to digest and may even be detrimental to your gut health.