Hi Illegal, possibly not enough
Not necessarily in terms of your feelings, if you don't think you love her absolutely don't feel drawn into saying that for both your sakes, but in terms of content.
Do you think you can relate to her some reasons why she's important to you or why you enjoy being with her??
But if you have real problems talking about things like that, and I'm assuming she's really understanding generally about that, maybe she'd be OK with you writing/giving her a letter saying how you feel do you think??
Afterall it's going to be a lot more than you've been able to say to her and it might give her some reassurance??
And maybe you could work with her in expressing your feelings (in other areas as well??) verbally a bit more, it might take time, but something to work on???
And you might find different things help with this e.g. different settings, different circumstances, timing, things she/you can say before/during that could help................???
Alison