Okay so the bad news: there's no route through BFB that completely avoids waking draugr. The barrow is designed to funnel you into combat encounters - the main chamber especially has sarcophagi positioned so you basically have to trigger them to progress.
The good news: your stealth approach can still work, just differently than the earlier dungeons. Here's what actually matters at level 8:
First, those Invisibility potions are clutch. Drink one, sprint past the main fight entirely if you want. Draugr AI won't chase you if they can't see you, and once you're past the initial chamber, the rest of the barrow is mostly empty corridors. You don't have to fight anything.
Second, if you do get spotted, muffle + crouching behind pillars in that main chamber can let you pick them off one at a time before they all aggro. It's slower than just fighting, but it works. The issue is they wake up in waves from the sarcophagi, so patience matters more than damage.
Third - and I say this gently - level 8 is pretty early for a pure stealth run on your first playthrough. You might hit a wall later where stealth just doesn't scale with enemy health pools. Not saying quit the run, just... be ready to adapt. My first stealth character got wrecked at Bleak Falls Barrow too.
If you really want to minimize combat, grab that Invisibility potion, use it in the main chamber, and just book it. You'll get through.
