Do you think you've maybe haven't waited long enough after breaking up with your ex before jumping into dating again? Only you would know but I recall you saying you were engaged? I would say imaging your ex when you're intimate with someone else isn't a good thing at all and has more to do with you than her (the girl you're seeing now.)But I like her being around. I enjoy the intimacy, touching, cuddling, stroking her hair, I wonder if part of that is having only left my ex partner recently. When she was lay on my chest after sex, I couldn't help but imagine for a moment that she was my ex. It felt the same. Her warmth, the embrace, it felt good to feel like that again but I don't know if it's anything more than that.
For me, I gave myself about 3 months before even thinking about dating but it was an emotionally abusive relationship so personally I really needed that time. As a result I never really had any issue imaging or comparing anyone to my ex. It may not be the same for you but that's just my experience.
Speaking of that relationship though, my ex said she loved me a little under a month after we had officially been in a relationship. Honestly I thought it was way too early for her to say that. I think what the girl you're seeing said about over a year is a little odd too but I think a few weeks to a month is even more weird. I just feel like at that point we're way to wrapped up in that initial rush of new relationship feelings to properly gauge how we feel. Anytime I've said I loved a SO, I thought back to it after the relationship had ended and realized I really wasn't in love. The girl you're dating sounds like someone who carefully considers her feelings and to her "love" means something far more significant than most people might. I think I'm a little similar in that way. I don't want to place an arbitrary amount of time on it but I'd say I need at least half a year before I could consider being in love with someone. Not because of the set amount of days but just the phases and changes my mind goes through typically in that time. I might really feel someone in the moment due to timing and other circumstances of that environment and then have that change later down the line (like summer flings or cuffing season or being in a good place or bad place relatively)
At the end of the day though, I don't know how much that would really Effect a relationship if she didn't love you quickly as you loved her. I guess you wouldn't hear her say the words but it wouldn't mean she didn't care deeply for you or show an adequate level of affection for you to feel loved. But if that is something that bothers you it's definitely something to consider moving forward.