1. Caballero and Alexis were lvl 4 at the time not five, and she didn't hold her own she just forced them to go all out since they thought she would escape otherwise. Also, when they got to lvl 5, she got instantly demolished.Skill is very possible, power is a maybe imo. Ella has repeatedly been shown to punch above her weightclass as well, she didn't even lose out too badly against 2 level 5s when she was level 4, and she was giving Nico/Gillibrand/randomchick a run for their money, basically toying with them and not receiving any significant injuries. If Gillibrand is capable of fighting with certain level 5s in duels, and Ella is capable of the same, except more, why is it then assumed that she definitely has less raw power, yes, it could be that she has just had the advantage of matchups so far and that she's highly skilled/knowledgeable about the ins and outs of supernatural powers and that makes it so she can do what she does. But she is also someone who can boost her power by consuming and we have no way of knowing just how much she's consumed over the time since she became a superhuman/level three. If this had been Malik/Bernhard/Henri obviously they'd have more but this is someone at level three where his growth is hampered by the fact that he's level three and not four or five.
2. She was winning in a 3v1 because she figured out a counter to Nico, Jill was scared shitles and was basically useless, and Duncan couldn't break through her invulnerability trick. Her win was a case of creative use of power, not raw power output.
3. You give to much importance to the feeding, we don't even know if it works that way for Ella. And even if it does, you only get one power point for it, and even that is not a given, since most of the time it gives nothing. For Mc to get 300 power points from feeding and to essentially double his power he would have to kill and AT LEAST 300 men, so about a small rural village, Ella, as a lvl 5, would have to devour entire cities to get any significant boosts to power.