Alright /ck/ I'm at the end of my rope. The milk won't curdle when I add acid. It's just simple fucking goat cheese how am I fucking this up?

>about 1 litre of 3.25% goat milk from store (getting close to best before date so it's fine)
>milk starts to separate as it's heated (stirring makes it homogeneous again)
>bring it to ~90 C
>add 3/4 cup of squeezed lemon juice
>nothing happens
>panic because I don't want to ruin another batch (13 fucking dollars for 4 litres)
>throw in a bunch of vinegar
>still nothing

The first batch I made with 2% turned out fine.