This is just a whine.

I go to The Sims 3 website and look for worlds to pirate build on, populate and taylor to my playstyle. I don't play with every single stuff and expansion pack active anymore because I'm trying to make it harder, e.g. okay with Seasons but NOT University and NOT Ambitions, can I play an alien and get rich? Can I master relationships without University? etc...

But while there's a space that shows what EP/SPs are supposed to be needed by the game, all the worlds on The Sims 3 are marked "base game".

I'm bitter about that. Open a game and find the bridges missing. I don't care if the Alchemy story is just a community house, but no bridges means broken routing.

I'm blessed this is my biggest problem in life.

Sorry to ask, but do you have like a question or this a "FUCK THIS THING IN PARTICULAR" kind of post? I think I can relate to both, although I can't recommend not having every pack installed if your computer could handle it.

Is there an easy way to find what worlds have what bridges from what EPs? I'm on my third downloaded world now. All have a bridge I'm not running.

Yeah, I guess I should just run with everything... Sorry.

Well my go-to solution would indeed be to just enable everything through the occasionally-convenient toggle menu in 1.69, and just disable the packs you won't need afterwards. But I'm not an expert.
And yeah, first world problems. Wouldn't have 'em any other way. I especially like the kind where the problems you have just get smaller and smaller and smaller, while kids in Africa are still dying of the same things they were dying of 100 years ago.
Wait, that's kinda dark. Didn't mean for it to sound like that. Moooving on...

I could be bad and say not being able to play that world is no great loss (!), but if you find one you love that is missing some bridges you can clone the world and put in whatever bridges you want.

I am on 1.67 and run with all except K Perry which I did not get.

Finding worlds on the exchange (if that's what you mean) is probably pretty complicated. There is little included in the way of information in general, much less more detailed information. It is really unfortunate that the exchange lists all worlds as base game only, regardless of what content has been used (but makes sure to mention if you need to buy store content). You could try to check out the World Catalog which lists some exchange worlds, as well as others found around. I believe you can sort by expansions too.

This is Great!! Thanks a bunch!

It really grinds my gears how the Exchange, TSR and many other small CC sites and blogs only post, like, one exterior photo for a building or a few scenery shots for an entire world.