5e has this lovely built-in math fix (which has a fancy name I can't remember atm) which basically makes your AC relevant for your entire career. 20 (or 21) is the absolute non-magical maximum a PC can ever have - and if your DM doesn't use magic items (and the game assumes they don't), you'll be okay. By comparison, Great Wyrm Dragons have somewhere around 25-30 AC and I believe only one or two deity-level creatures has over 30.
By that same math fix, your DC's aren't "low". They're where they are expected to be. Assuming a 16 Charisma, your spell DC will be 15(ish - IDHTBIFOM). Many of the Bard's charm/debuff spells are (I think?) Will-based, and most creatures proficient in Will saves will likely be rolling at +3 or +4 to save... but most others will be rolling at -1 to +1. If you're that worried about spell saves, don't cast spells that require them - Buffs, Healing, Information spells and your Inspiration ability do not require saves.
Really, try not to focus too much on your numbers. Stressing about them causes... well, stress. Our party has four warriors on it, two of them Paladins (I'm going dual-wield and will likely huck daggers/darts as my ranged jam). You could easily do an Archer/spell-build and have zero issues. In fact, you're the only Arcane caster on the party, so go for it. We'll cover your Half-Orcish arse.