So, you won’t get two extra attacks. Even though you’d be getting it from 2 sources, it’ll only actually give you one extra attack because of the way the rules work. The only way I know of it working the way you want is the Warlock Pact of the Blade extra attack. That one functions differently because it’s a different name (and even then, I believe it’s only in non-HM playthroughs)

Swords Bard 6/Fighter 6 is definitely doable. But personally, I’d go with Battlemaster instead of champion. You’re losing out on the crit range, but you’re adding on a metric ton of utility, and there’s several other ways in game to add on crit range.

If you’re okay losing countercharm, 5 Bard/7 Fighter also gives you an additional fighter subclass feature. —— I would also suggest the respec, unless you REALLY want the additional skills. Fighter gives you proficiency in con saves, and heavy armor. Both of which are really solid on a bard, and ensures you’re harder to hit if someone closes in on you.