Well I played the character over 10 hours so..
Honestly 10 hours isn't much. It took me over 28 hours to get to level 25 on my current warrior character. That's about the point where you really start getting a feel for a class. It takes having quite a few perk points before you really know what works and what doesn't.
For me a companion is a waste on a sneak character. They break stealth too often, attack when you don't want them too, and generally get in the way. They also won't drop combat once engaged making it very hard to slip off and drop back into stealth. Stealth characters are already the most powerful class in the game. I you need a companion to take something down you're not doing it right.
Since you're already focusing on sneak, Dual wield sneak attacks are way more powerful than going in standing up. Use archery when possible but if you want to go melee do it from stealth. Or just use your stealth roll to get out of range, drop back into stealth, and sneak back for another archery attack.
I will agree that later in the game, with the right perks and gear, standing toe to toe duel wielding is extremely powerful. Best to use dual swords for it though as they typically put out more damage face to face than daggers.