Is it normal if i'm with him for the challenge?

Soooo one of the main reasons why I'm with my current bf is because he makes me want to be better but at the same time, I feel uncomfortable at times and intimidated. I feel like I'm not good enough for him but he makes me want to work for it. I know that with him, I'll learn new things and become this more confident, smart person. But my flaws have def taken a toll on our relationship and its mostly on my part. It's not like he directly tells me I suck and need to be more of this and that. It's more of the voice in my head and that voice distracts me from just letting go and enjoying the moment with him. But that voice just doesn't appear out of nowhere. I can tell from his reactions and attitude that he wishes I was more of so and so and it kills me inside because I know I have potential, it's just not there yet. He def makes me feel insecure but I don't think as an individual, I'm an insecure person.

Considering my last relationship, I was very confident. Part of it was cause I felt really comfortable w him and like I can be myself no matter what. He wasn't going to tell me nothing. Yeah I felt good but at the same time, I wanted someone to tell me NO. As said before, its not like my bf now does literally tell me "no" but he's for sure not a doormat like my ex was so I find that really attractive. Not just attractive about him but attractive in terms of me bettering myself. I know I have these flaws I want to get rid of and my ex made it seem like it was okay with what I was doing. With my bf now, its clear that it is not okay to do...even my family and friends notice Ive gotten more mature and A LOT has to do with being in this relationship. But the downfall is that yeah, sometimes I feel insecure, like I can't be myself, so is that just me being out of my comfort zone and taking a challenge for the better? Or is this straight up just me being lost, confused and insecure? and I should move on?