What I would do is, explain to her the situation while you're both rolling.
Like,
"Listen I want us to be clear on something ... I feel really good about this relationship even though it really hasn't progressed all that far just yet, and I know it's too early to call it real love but right now I feel GREAT about you and you seem like a really, really fantastic girl and I'm totally sold! And I really hope that in the future our relationship blossoms into real love and I know that the only thing that keeps it from being real love right now is that we haven't known each other long enough to really 'get there' yet I guess, but I WANT to and I'm willing to put the work into the relationship that will get us there. Before we took these pills I was already really happy that you were in my life, but I was worried that the pills would put emotions into my brain that I wasn't ready for, and now I'm rolling and you're rolling and we've got all these emotions between us because we're rolling and I'm ready to feel these emotions all the time and I want to, and I know that after we come down we might not feel these emotions again for a little while because we won't be rolling anymore, but I also know that if we care about getting closer to each other, these emotions will develop on their own, without us needing to take pills, and then this relationship will be what I think we both want it to be, and I just wanted to show you that I felt this way and I wanted to also ask how you feel about me? And I think if you say you love me right now I'll just think it's the pills, but that's OK, because I ate pills too and I love you right now too, and we'll both come down and maybe it won't be the same tomorrow as it is today, but that's OK too, because if we work at it, this relationship can become like this all the time! And I'm excited about that. ::deep breath::"
That's just how I'd imagine a rolling person who felt the way you do would say what I think you might want to say.
Good luck! Just, seriously, really ... DON'T be scared to tell the WHOLE truth.