You are so worried about the seating chart. Table nine, the two cousins who don't speak, whether the vegetarians will feel forgotten. I can tell you now: nobody remembers where they sat. Not one person, not ever.
Here is what they remember. Your uncle, who you were sure would give a stiff little toast, gets three sentences in and has to stop, and pretends it's the microphone. Someone's shoe comes off during the dancing and stays off for the rest of the night. The cake is fine. The cake is always fine.
Go find your grandmother at the edge of the floor, the one holding her cardigan closed with one hand. Ask her to dance. She will say no, she will say her hip, she will say she's too old for that. She will let you pull her up anyway. You will be embarrassed by how slow you have to go.
That is the part I would trade a great deal to have back. Not the vows, which were lovely, and not the photographs, which are in a box somewhere. The slow shuffle with your grandmother, her hand light as a leaf on your shoulder, the song ending too soon.
Fix the seating chart if it settles you. Then let it be. The day was never going to go the way you planned, and I am so glad it didn't.
Dance the slow ones.