So I'm playing with all these mods
TIE
Guard Overhaul
Stealth Overhaul
Thieves Arsenal
Tamriel Travellers
Snipesneakskillup
Bank of Cyrodiil
Vaults of Cyrodiil
Thievery in the Imperial City.
and wow does it make it hard. Right after I got out of the sewer (after dying a handful of times) I went to the first "dungeon" and had my ass handed to me. Maybe I'll go around the city and take on the main quest line first

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Just some food for thought, and I realize being new to this you won't want to be doing anything drastic to change this yet but the OMOBS weapon system used in OOO and FCOM increases weapon damage in general, which coupled with Sneak Attacks and good stealth-stats make guerrilla combat extremely possible; you can snipe that bulky bandit very quickly and take out his friend before he gets to you. In general you want to realize that stealth characters want to avoid getting hit more than land a lot of hits, and as such dealing quick, instant damage is very helpful; you'll still be just as challenged by other archers and mages, who utilize the same tactics, but it not only makes stealth invaluable (first blow is important with higher damage), it also lowers melee combatants on the food chain.
I'm not telling you you should jump on an FCOM install now, I'm just noting in general that this is useful. If I recall a mod was released recently (last 2 months) that uses script to double all damage done to or by an opponent. This would probably be something worth looking into, and also something I should list

Also worth noting; along the same train of thought as what I was talking about earlier, I feel making arrows and magic bolts faster (via Bashed Patch there is an option to do so, I believe) is worthwhile, but you may feel like melee fighters are underpowered then, so it's your call.
I hope that may prove helpful!
At the 10 hour mark of my last game I was a pure stealth character (Agility + Speed, all of their related skills and Blade on a Wood Elf) I hadn't died once, and had already done the first few SI quests and wondered a good portion of the map, and that's with all the mods you listed installed (except Thieves' Arsenal) AND a full FCOM setup. I'd like to think it's simply because I'm awesome, but really it's just application of the tactics forced on you by the engine, which I feel are more well balanced with higher damage.