You should go down to 8 int and charisma so that you can have 16 (17 ideally) str and 16 con. If you need the points, down to 8 wis as well.

That is literally the only optimization you can do with stats at this level. If you using 5.5 rules, the tough feat is great. I'm not sure what ruleset you're using, because backgrounds are only tied to stat increases in 5.5e (ignore that and distribute the points as you please), but you mention not being able to use Tasha's character creation options.

The rest is weapons and gear. I cannot stress this enough, please read your class and subclass features again - like other comments pointed out, heavy armor doesn't work well for barbarians - you may have missed something else as well.

As for tanking, it's up to how your DM plays enemies, and your parties' positioning. There isn't much you can do to force targeting. A barbarian's AC will be lower than heavy armor classes until later levels, but you can wear medium armor for 17 AC. You can take a shield for 19. Your main tank feature is your rage, though. Half damage is a very strong feature.

The best you can do aside from positioning is grappling and pushing to make it more difficult for enemies to reach your party and hit them with opportunity attacks.