I would describe the OP's dish as being neither pasties nor patties.
The most well known type of pasties in the UK are called Cornish pasty
Wikipedia defines a Cornish pasty as being:
... shaped like a ‘D’ and crimped on one side,
not on the top. Its ingredients should include uncooked beef, swede
(called turnip in Cornwall), potato and onion, with a light
seasoning of salt and pepper, keeping a chunky texture. The pastry
should be golden and retain its shape when cooked and cooled
I believe the dish cooked by the OP does not resemble a pasty in the slightest.
Patties don't quite work for me either. There is a popular dish in Jamaica called, interestingly enough, Jamaican patty.
In the article the patty is described thus:
... contains various fillings and spices baked inside a flaky shell,
often tinted golden yellow with an egg yolk mixture or turmeric. It is
made like a turnover but is more savoury.
In Italy this type of stodgy finger food is virtually non-existent and has never really caught on in fashion. However, if an Italian had to describe the OP's snack food, they might describe it as being vol-au-vents. Vol-au-vents are always made from puff pastry, the small, golden-coloured shell cases are usually filled with a creamy savoury filling.
However, in the UK, as Barrie England pointed out, they would be recognized simply as sausage rolls, i.e., puff, flaky or short crust pastry, filled with sausage meat, rolled and baked in the oven. The most popular rolls are in fact made with sausages, but there are many variations on this theme, and not all of them need to be savoury. Due to their bite-sized portions they'll often be called mini-sausage rolls.
Comparing the photos of the mini-sausage rolls with that of the OP's it seems pretty clear to me that the two snack foods share many similarities.
If one wanted to impress their guests with a fancy sounding name, I'd opt for vol-au-vent and call the mouthwatering dish, Beef and mushroom vol-au-vents. Otherwise, if your guests are unfamiliar with the term Paszteciki, I would suggest the more British sounding Spicy beef mushroom rolls
As Jolenealaska says, we have no such word. Non-mothers is perfectly acceptable and understandable; but as you discern, it’s sort of clunky.
But since you have already identified the category with which this category is contrasted, you need not give it an explicit name. Just write:
[Herb] increases the quantity of breast milk in lactating mothers, but other women can also take the herb ...
I’ve added lactating, since you presumably want to include mothers of older children in your second category.
Best Answer
Such a mother can be called a "lactating" mother or, less clinically, a "nursing" mother.
Note NGram distribution for three terms, including yours:
As you can see, "breast feeder" flatlines, the arc of "lactating mother" suggests a restricted, perhaps technical usage, while "nursing mother" has been much more widely used and for much longer.