Instagram Feed

I am having difficulty displaying the correct number of posts from my Instagram feed. I have three breakpoints (1001px and up (Desktop), 751px - 1000px (Tablet), and 320px - 750px (Mobile).

I would like the feed to display 3 Instagram posts on Desktop (1 row, 3 columns), 2 Instagram posts on Tablet (1 row, 2 colums), and 3 Instagram posts on Mobile (1 column, 3 rows).

The Mobile view is absolutely fine and works, however if I change Tablet to 2 columns this automatically alters Desktop as well - it doesn’t cascade down. Does anyone have any ideas on this please?