So in the end, I just don't really see how Dany could conquer Westeros, because I think her dragons would eventually be killed off here and there, before she could take all of the territory that she wants, and her army is already at a disadvantage

Dany doesn't have to conquer Westeros. If the show is anything to go by, all she has to do is show up and everyone is going to go over to her side in a "glorious revolution."

Consider:

She has the Tyrells already, and Dorne (once Aegon is dealt with). The Lannisters have burned the bridge with the common people, nobility, and the faith, and are going to be extremely short on allies. The North is in outright rebellion again. The Ironborn are inconsequential strategically.

Dany just needs to show up, wave her flag and dragons around, and everyone is going to say "thank god you're here, not having targaeryns around was a disaster!" and they'll hand her the throne on a plate.

This presumes Aegon is dealt with. If he has successfully seized the Stormlands, she should marry him and then rule Westeros together, with their children heirs to the throne. If he's dead then its a non-issue. Dorne will go over to her easily enough, and if they don't they're also not a strategic threat.