I'm a little late to the party, here----and, I see you've already found something you like----but, in case they don't work-out because of the stains.....
I've been in the fashion industry, off and on, for over 40 years (designed / made clothes; been a consultant / stylist); and, one thing's for sure, is that weddings, "after 5", and evening wear are very closely related, in that suede or leather, like the model in the OP is wearing, should NEVER be worn----but, rather, fabric. My FIRST thought, was to get satin / fabric shoes dyed to match----the style in Dianthus' FIRST link, were PERFECT, IMO----'cept I, personally, would never wear / suggest such a contrasting color, and you said you need straps.
The SECOND thing I thought-of, was FLOWERS:
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Those shoes / bag are sold on Etsy. They have a heel like I think you'd like, but they don't have straps. (I'm thinking the problem with you walking out of your shoes, is you're getting them a tad too big. Heels push your foot forward, and will leave a space at the back----I'm thinking if you got them a half-size smaller, that might work.)
The shoes in the link I posted, above, are a little too dark, for MY taste (they might be totally fine, for you); for myself, I'd choose something along THESE lines:
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THESE (in the following link) are FABULOUS, IMO----BUT, they're SUMMER; so, unless you're "Down Under", I wouldn't choose them:
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These (in the following link) are another, fairly good example----except I wouldn't wear squared toes, for a wedding; and, the bag is not structured-enough, for such an occasion:
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If you're a crafty-type of person, I would go and buy FABRIC shoes / structured bag (clutch), and PAINT them with flowers (I'd totally cover-up the white background----unless, like I said, it's summer)! I've done it before----and they turned-out FABULOUS----just make sure you use FABRIC paint (don't use plain ol' acrylic, cuz it'll crack / flake / fall-off), and a MATTE sealant.
That dress, in the OP, is BEAUTIFUL, BTW!!
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White female; age 59; diagnosed Aspie.
I use caps for emphasis----I'm NOT angry or shouting. I use caps like others use italics, underline, or bold.
"What we know is a drop; what we don't know, is an ocean." (Sir Isaac Newton)