Wedding guest dresses from Amazon in navy blue, but come in a lot of colors. These are all petite friendly as midi dresses, size small. i'm 5'1", 108lbs. The first two dresses run like xs/small. The last one is TTS. I linked my favorite strapless bra. Two strap heels run TTS.

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Commissionable links
oten Womens Sleeveless Deep V Neck Sheath Knee Length Cocktail Party Work Faux Wrap Formal Dress | Amazon (US)
GRACE KARIN Women V Neck Ruffle Sleeve Ruched Business Pencil Dress at Amazon Women’s Clothing ... | Amazon (US)
GRACE KARIN Womens Off Shoulder Cocktail Dress Asymmetrical Neck Long Sleeve Slit Pencil Dresses ... | Amazon (US)
Charming Tailor Faux Suede Clutch Bag Elegant Evening Purse for Wedding/Prom/Black-tie Events (Nu... | Amazon (US)
Natori Women's Pure Luxe Custom Coverage Contour Bra | Amazon (US)
The Drop Women's Avery Square Toe Two Strap High Heeled Sandal | Amazon (US)
b.tempt'd by Wacoal Women's Modern Method Strapless | Amazon (US)
Yoosteel Gold Initial Necklaces for Women Girls, 14K Gold Plated Dainty Layering Paperclip Link C... | Amazon (US)