@aSofaNearYou - I think what you describe is at the very heart of things! Others have commented that including her in the wedding plans was not a particularly good example- somewhat insensitive and all about OP, not SD. And doing the school run is not exactly going to be experienced a nurturing activity either.
If OP has examples then it would really be worth reflecting on those with her SD - discussing the efforts made and the attempts to offer love and support. My interpretation of what OP has said is that there aren't very many examples and the ones given don't really show 'more than adequate' - the wedding being insensitive, and the school run being perfunctory.
The OP reflects herself that she could have done more, and behaved differently. But perhaps there were genuine efforts and, if true, SD should be willing to acknowledge those times and her response, and find a mutual understanding of where things went wrong.
But what you've defended as 'more than adequate' really isn't. You think it is - I think it isn't. I can give you many reasons why I think it isn't enough, why becoming a step parent is a major undertaking and why no-one should expect to just set off as a happy family without a lot of foundation building.
Step parents don't get a let off because they aren't the biological parent. Of course it's a different relationship, but it requires no less care, attention, nurturing, teeth grinding, patience and effort.
The Dad has a lot to answer for, for sure! I'm not sure where to start! But it's OP that is now suffering the hostility of SD - much of which lets him off the hook!
I suspect that if OPs efforts had been more than adequate, she wouldn't be here. She would have been able to reflect back on all those times she attempted to engage and forge a better relationship, and SD would remember her inability to reciprocate.
My advice remains the same - OP needs to recognise and be open about the failings she made, validate the emotional hurt that her SD experienced from not being loved like the other children, and find a mutual understanding of the difficulties they both faced.