I feel like she doesn’t value my opinion

My sister got engaged last October and she said the wedding will be on August or Sep of 2023. I have offered me to help her but every time I show her something that she might like for the wedding she tell me, I’ll let you know if I want that because my boyfriend and I don’t have a list of guests yet. Do you think that I need to back off? I feel like she doesn’t appreciate my offers