Hi Illegal, no honestly no sarcasm
I think she probably does want to know (want's to be told?) that she is important to you. I really don't know if you're right about the "L word" but knowing she's important to you I'd say might matter/make a difference to her if she's feeling insecure/wanting to know.
And if you haven't been directly letting her know then maybe there's some insecurities/uncertainties (?) there. IMO I could "get that".
But about letting her know she's important............I was thinking more about what she does for you as opposed to what you want/want to do for her. You know why do you want those things for her, why do you want to do those things for her............
I'm sorry I'm probably being confusing now, am I???
But for instance..............is she someone who makes you into a better you?? Is she someone who is special to you, who makes your world better or "brighter"?? Is she someone you feel you can be the "most yourself with"?? Is she someone you feel you are closer to than anyone else (right now)??.............you know that kind, or something like that kind of thing
And without her...........(and use your discretion on whether you want to do this bit!!!) could you say that if you didn't have her your life would be "emptier"/"so much duller"??
Anyway those are just some suggestions/queries..........if you put things into your own words/how you feel, clearly you already have something that matters with/for her so if you can build on that???

Alison