Excluding immediate family?

My FH and I have pretty killer social anxiety and are really trying to keep this smaller than possible. We only recently changed our minds on having a wedding at all, otherwise it wouldn't happen.

We are considering two options:

* just our best friend and her partner, FH, myself, and our two daughters (+ officiant & photographer) total of 8 people

* SIL, her husband, their two sons, BIL, +1, my brother, +1, best friend, +1, FH, myself, our daughters (+ officiant & photographer) total of 16 people

He doesn't get on with his father and step mother (nor do his siblings, they will not be invited). I don't particularly care much for my mother or father, but it would certainly hurt my mother's feelings to be left out (we were excluded from my father's wedding a year ago). I have grandparents that I'm very close to. My grandfather may not make it to our projected wedding date. My grandmother would be upset to be excluded, but she'd almost certainly be accompanied by my mother. The two of them would be the odd balls out, likely without plus ones. Although, my grandmother wouldn't be upset at all to miss it if our wedding took place in a courthouse with only us and our witness.

To be quite honest, the only reasons we're even having a wedding is to use it as motivation to lose weight and for photos sake.

Thoughts?