See, I'm gonna tell you a funny story because I see you are struggling as much as I did before.
Your post, is actually similar on why my girlfriend and I started dating lol. I'm 23, she's 24, we've been together for almost 3 years, but we knew each other since we were 15 and 16, so we've known each other since then.
I've known for a long time I was pansexual, even before meeting her, but I'm more inclined to girls. Like, at a 98%. Anyway, at first we were BFF's, but we started to develop feelings for each other. We never made it clear on the beginning though, we just called each ohter "wife", nothing gay about that right? ;) Just gals being pals...
We were not dating or anything, but she got into a relationship with a shady guy. Worst time of my life, because I had such hard feelings for her, so I felt like my life was falling down because of that but I couldn't do anything about it because of course she didn't know I was in love with her.
Thankfully she broke up with the guy, and time later I talked to her on how I felt that she was dating another person. I told her that I loved her and she got happy and told me she loved me too and in the end we didn't do anything about it and continued being BFF's but we still had a "more-than-friends" kind of love, if that makes sense. Years later passes (I think we're 20 at this point) and we finally confess to each other that we have some sort of platonic love. Yes yes you can laugh I mean, so many years and we said only platonic love.
Now the time passes and I'm the one that is in the process to date a guy. When I told her about it, she got very sad and then she confessed her love for me and I confessed her back, because of course I still loved her. I left the guy since we didn't even start dating or anything, but she and I still weren't girlfriends even though we loved each other so much because we both were afraid to stop being BFF's, like, we both cried everytime just thinking about breaking our friendship and something happening and we never being able to see each other again. It hurt the both of us to think that. But we managed to get over it with the time, and now we're girlfriends! I still love her as much as I did the first time we meet.
So... my answer to your question is, I think you love her romantically, not platonically. Of course it depends from person to person so I'm talking with my own experiences here, and how I felt back then. You don't need to love someone "sexually" to be in complete love with them.
If I was you, I would tell her. I mean, when I wasn't dating my girlfriend I was literally calling her my wife and the love of my life and we were still BFF's so... lol. I'd say go for it. You won't know if you don't get your feelings out, and it's better to know and let your feelings out than to always regret for something you didn't even do your whole life, you know?
I hope I was a bit of help, best of luck with your situation! Sending you lots of love and support <3