I was on a 2GB data plan for most of this past decade, despite being terminally online, it never really got in the way. Would still share pictures immediately, they aren't that big (and most services compress video down to too horrible quality for it to be worth sharing). Still never managed to hit 2GB in a month.
The vast majority of my data usage now, on unlimited, comes from watching YouTube.
Switch to a data plan with less than 2GB of data per month and you'll be a lot more thoughtfull about how much you post instantly. You may still post it but you'll do it when you get home; just like the old days.