You probably don't need to worry about having put her into a guilt state of mind. People are actually a lot slower to feel guilt than you think.

That leaves you with two possible problems that are realistic. One is that you really do have an excessive fear of abandonment, which I think you probably do have. The second is that this new girlfriend of yours really isn't the type of girl to make a guy feel secure. My guess is that it's a combination of those two things.

You probably can't talk yourself out of having this fear of abandonment. That's part of who you are, at this point. It will possibly only go away, if it ever does, when you find a really satisfying relationship that becomes truly permanent. Unti then, the best you can do about that tendency is to tell yourself that losing a relationship is not the end of the world and will not kill you. Losing the last girl hurt, but life went on and you found another girl. That may have to happen a few times before you find "the one." And that's okay. The upside of that is that a series of relationships might actually lead to you finding a more compatible person than if you fiercely held on to the one you are in. You wouldn't necessarily buy the very first car a salesman shows you. Lots of people go through a series of failed relationships, before they get in one that sticks. When they finally get into a permanent one, they usually look back and are glad they moved on from those earlier relationships. (That was my own experience.)

Then there is that second issue of this girl maybe not acting in a way that would make any guy feel secure. I suspect there is some of that going on. She may be the type who just has to have a boyfriend and will try and hang on to a guy, even though she is not that into him. Her thinking may be, "I'll hang on to this guy, until something better comes along. There actually are a fair number of young women who will do that, and I've known some. Often they are prettier than average and figure they can just try guys out, but keep shopping the market. It wouldn't be wrong of you to test this out. You might tell her that you're not going to hang around, while she pays a lot of attention to her phone. Then you have to back that up with action. If she is really seriously into you, she will put that phone down. If she doesn't, then she is saying she can take you or leave you. In that case, you might want to move on yourself. Don't be the kind of guy who always leaves it to the girl to decide to be the one to leave. If a girl is not making you feel pretty special, then you may need to say, "I want better than this." Doing that will actually build your confidence. Don't be willing to settle for whatever crumbs of attention a girl will throw you. When you really care, give a lot, and expect a lot back. That's okay.