Thank you for your thorough reply!
I've heard from many people that even though universities don't say it out loud, a lot depends on who writes your recommendation letters. To explain it more clearly: many professors recommend their undergraduate students to the other professors, who they know personally, for a PhD. I'm certain that this isn't the way it always goes, however since research resources in my country are relatively scarce and my professors aren't published in journals with high impact scores (in fact, most of the researchers here are lucky if they get published anywhere) that worries me. I'm anxious about not being dismissed just because that my grades or recommendation letters are not "trustworthy" enough. For example no one from my university has ever been accepted to a PhD program in the united states, maybe I shouldn't be as worried as I am right now I don't really know.
I'm trying to reach out current students in different universities but this process is very challenging and I don't know any easier way. Thanks again for your help!