so today i had a pickup for a flower cake someone had seen on my website and i sent her another picture of a cake that i thought had a nicer color scheme, i meant to say that it was gonna be the same cake she liked with this new color scheme but i just said... "isnt this one nice?", she exclaimed how much she loved it and we agreed on a price (what i normally charge for a small cake).
the original cake was one tiered, square and small, the cake i sent her was 2 tiered and would probably feed double the first order.
when she came to pick it up she asked where the second tier was.. i explained i meant the color scheme not the exact cake. she understood it was a misunderstanding that can occur when placing an order, she paid me (what i would charge for a one tiered cake to feed 40 people, not 70) but now i feel horrible that i didnt meet her expectations.
what do i do?

You've got her email, so it might not hurt to send a follow up - "sorry again" - but really I don't think it's a huge deal. I think surely we've all made odd little mistakes like this that make us cringe, but I wouldn't give that one much energy. She got a nice cake, that met her needs.

I know if I was the woman I would have been so excited thinking you were going to do that cake for me, thinking it was the same price we had agreed on. And, yes I would have been so disappointed when I picked it up. Then I would have felt stupid for not understanding correctly.

If I received an e-mail from you saying you were sorry there was a mis-understanding in communication I would think how nice of you to follow up. There are not enough people out there that care how someone may feel.

This is why I do not do all of my communication through emails. I type what I think I am thinking but that is not how the other person is reading my email.