A.C.
Hi N.~ I wish I knew of a group, but I don't. Most play groups for that age range happen in the morning before naps, when the kids are bright-eyed and not so spent from their busy baby day. Two suggestions... I know you are working, but many hospitals have a "new mom's group" that meets weekly. You probably couldn't attend that, but try and get in touch with the facilitator, or maybe try and make it to one or two meetings, to see if other mom's with babies would be interested in starting an afternoon/evening playgroup. You can also check meetup.com for playgroups in your area.
Good luck!