Hey @Eric,
Even if you’ve known each other for a certain time, being committed to her seems to be something new. Your relationship has been taking a different shape for two weeks now, by making it official. And I think it’s really normal to second guess it. I think it’s something that a lot of people experience, more than it’s generally said. Just because it’s a change in your life. It opens new doors and it closes other ones.
If you’ve been used to be single for a certain time, you’ll also need time to adapt yourself to this transition. Yes, you leave things behind you, but you also walk towards different opportunities and experiences. Sometimes we can be tempted to step back because what is behind us is familiar and what’s in front of us is still quite unknown. Though, the balance between living your life and being involved in your relationship is something you could learn to build together, if you want it. Maybe it’s just difficult to imagine it right now. Even if you’d be involved in other relationships before, and even if you know her well, it’s still a new experience, with a unique individual.
What I see in your message is that this person matters to you, which makes this commitment even more stressful. But your two options might be a bit extreme. For what it’s worth, I think keeping secrets (about your relationship, not in general) and hoping that your feelings will fade away can be very risky. Because if you keep feeling like this, you could end with holding resentment towards yourself and her, even if you don’t want to.
It’s a personal perspective, but I truly believe in the positive effects of honesty. But there is also a way to approach it, a way to share your heart so it doesn’t feel like rejection. Even if you push her away, it doesn’t mean that’s what you want. But it certainly shows that you’re a bit divided in your heart right now. And as you are at the beginning at your relationship, you are both learning to trust each other. It’s a good time to be honest and make sure you’re on the same page. Just take your time to think about how to express those things in a way that could allow you both to grow together. Because there’s a third possibility here: moving on together and taking account of how you both feel in regards of your relationship. Who knows… maybe she feels a bit the same but doesn’t say it? Which doesn’t mean there’s no love, that one of you did something wrong or you don’t want to be together. It’s just human to have hesitations. And it’s actually positive to be aware of those to make your own decisions.
After 7 years of living together, my sister and my brother in law had a difficult season. He was missing his single life and was stepping back. He was afraid to miss opportunities, experiences, other people to know because he would be committed to one person. It really matters to him to be sure that he lives his life fully, with no regrets. Making decisions has always been a real struggle to him (I can’t cound the amount of time we spent when we waited for him to chose something to eat at a restaurant or a movie to watch 8)). But more seriously, this almost led him to have a relation with someone else. And after 7 years of living together already, it was tough for both of them. He had to reflect quite a lot on himself and make a decision. We discussed a lot, to understand why he was feeling this way. They’re still living together. It’s been almost 15 years now. They seem happy, they have life projects, they even got married in the meantime. And if they didn’t address that together, they’d probably be separated right now.
This could be a good opportunity to build trust. And as Sapphire said, making sure that you don’t place blame anywhere is a major point. Because there’s no blame here, really. I really think that you can try to discuss and see how you can progress together, with respecting both of your pace. There is no need to rush if you feel the need to take your time. And if you are both willing to move towards the same goal, then I have no doubt you’ll manage to move on together, step by step. 
