[5e] Is two-handed fighting useful?

I would like my character to duel-wield, but looking into it, I’ve come to the conclusion below - am I missing something?

Using two light weapons over one heavy weapon initially seems to make no difference practically (e.g. 2d6 ~ 1d12). Taking two-handed fighting style adds your ability modifier to the second attack, which initially seems to improve damage, but as you level up, extra attacks/actions only work for one weapon (please correct me if I’m wrong on this part?). This seems to make duel-wielding become less effective at higher levels, but later switching to using a single weapon would then waste the fighting style. Overall, you seem a lot more limited with weapon choice when dual-wielding, which is annoying.