Can anyone help me style this dress in a 60's/70's way?

(F18, 160 cm)

In a week I'm going to look after my niece to my sister's friend's wedding. It's gonna be outside the house I'll be staying in with the kid, so I want to look presentable because it's certain that the guests are going to see me eventually. So it won't be the typical wedding outfit. I thrifted this dress just today and I don't really like how long it is, it's reaching my knees and it's slightly too wide and looks unflattering, especially from the side. I'm wondering if I could try to sew it or just go along and add some accessories, not minding the length.