Hungry baby!

My 7 week old has 4oz every 2-3 hrs but recently she's been crying for more, so I've been giving her 5oz but she ALWAYS brings some back up 10mins afterwards, she won't settle if she's not had this extra oz, I'm burping her correctly and I always keep her upright for 20mins after every feed, so the only thing I can think of is that her little stomach is full and so she's bringing it back up, but if that's the reason then why is she crying for more milk?! I don't have a clue what to do about this, should i just let her carry on throwing up cause it's not masses amount?!