I'd keep doing the flowers bit, and maybe some gifts to work. Perhaps 3 times a month if you can afford. Its interesting that the peer group will see your effort and sincerity. I believe over time it can be a "fog clearer", because her peer group will obviously see the guesture and she will have to do her mental magic to make herself think its irrevelent or a manipulation. Over time the reality should start to winning out.
Also I would occasionally invite her to lunch dates.
Keep doing everything else your doing, sounds good and it gives me motivation in my situation.
By the way, we all usually feel the same way like the effort will not work. What has been given to us is principles that work over time, so if there is a chance it is through these methods.
