My bf is 16 years older than me (I'm 22 and he's 38). I was invited to a bbq to celebrate the father's day with his family. What should I wear? He has two brothers, both of them married with women their age, so I don't want to look too 'young' next to them (but I don't want to look old either). I don't want to wear heels that day. Any suggestions? Pics with outfit ideas are welcome :)