I've gotten her used since day 1 to not be possessive of toys, bones, food, anything. A human can take her bowl away and pretend to eat it, and she'll sit and wait with her tail wagging.
I would personally stop doing this right away. It's a method that's unfortunately gained traction online, but can backfire badly with the wrong dog, creating an issue that never would have been there otherwise. A dog that trusts you not to randomly take things away for no reason after you've already given them to her is a dog that has no reason to ever become possessive. Taking away her food and giving it back to her, or messing about in the bowl (I don't know if you do that, but some people do) isn't necessarily showing her that it's okay and she needn't worry. So do some training around mealtimes, have her practice impulse control behaviors and hand feed her a few pieces while you maintain possession of the bowl, that's all fine. But once you put the bowl down and let her have it, it's HERS.
Dogma has it right, this sounds like resource guarding to me too. You're the resource. Dogs that are not at all possessive of stuff in general can still resource guard their humans. Keefer does it at mealtimes, he's barked to warn off the other dog ever since we got him. He's 13-1/2, nearly blind, and almost completely deaf, but darned if he still tries, lol. It's never been a huge issue so I've never worried about it, and at his advance age, he can do whatever he wants. Dena ignored him, Halo was the queen of the house and she practically rolled her eyes at him. If she were human she would be saying "yeah, yeah, you're the boss, dude, whatever you say" in her most sarcastic tone. And then she'd go right back to owning him once they were done eating.
When he barks at Cava to warn her to stay back while I'm putting their meals together she just barks back. It's incredibly annoying to have both of them barking at each other, but it's a few minutes twice a day so I can live with it. THANKS, Keef! The good thing is that none of his three sisters were the slightest bit intimidated by him and it was clearly never going to escalate into something that needed to be addressed. It also only happened at home, at mealtimes with our own dogs, never at the park with other dogs around.
Is she jealous? Is she scared I'll like another dog better and she will lose me? Is she protecting me from a potential threat (since she got attacked by her father at such a young age)?
Not jealously per se, nor is it likely she thinks she'll lose your affections to another dog. That implies some complex emotions and logical forethought, and dogs are more about instinct and living in the moment. But she does clearly value you as a resource (food, play, attention, etc.) and she could also be somewhat insecure, especially around adult dogs, causing her to react the way she does. I think it's extremely important that all of her exposure to other dogs be very positive, in order to build up her confidence. Remember that exposure and interaction are not the same thing - she can be socialized to a variety of people/places/things/dogs without actually interacting with any of them. If fact, if she does lack confidence, it will make her feel more secure if she knows she doesn't have to. I think some basic obedience will help too, and having a familiar routine when other dogs are nearby, such as what dogma describes. The more she's allowed to practice the behavior the harder it will be to extinguish so I would not put her in situations where you can't control the environment.
At 14 weeks it's not too early to look for a beginning obedience class. Do you have any good facilities near you?