worth it?

I’ve been dating a girl for 11 months now, and this is the first girl I’ve ever been with. I love her, I think shes great and I love her family and im very attracted to her and everything. lately shes been bringing up marriage and living together and things of that nature and its putting me in a dilemma. she cheated once, very early in our relationship, and she said it was a mistake and I forgave her and I feel like shes made a real effort to make me believe it wouldnt happen again. and it hasnt been brought up in quite a long time. but now that shes getting a little more persistant with the marriage talk I cant help but think that there might be someone better out there, especially since shes the only relationship experience I’ve ever had! and now it seems like all the imperfections about our relationship are starting to get magnified to me, and being single is starting to seem very appealing. so heres the real problem, I honest to god love this girl and have always been thankful to have her in my life, when im with her I just have this feeling that she is special, but at the same time I really want to explore a lot of curiosity I have about being in relationships with other people, and I cant help but think that she hasent exactly lived up to her end of the bargain since we decided to start a relationship. I know im going to second guess myself big time, regardless of which desicion I make, but it just seems like there is no right answer to this one. any insight?