Bin these arseholes off! Nasty pieces of work! I very much doubt THEY are perfect mothers!
Such groups really aren't for the babies at 7 months he really won't even notice much less care!
Find another group, post on here stating roughly what area you're in to get recommendations maybe or check local fb pages
Have you no other friends that are parents?
This brings to mind my experience where I went to a local mum & toddler group I was recommended - they made a real point of getting my address out of me purely so they knew what kind of housing I was in. Then turned their noses up and wouldn't interact with either me or dd.
I was much less bolshy then! I left in tears and broke my heart at home. Then husband was livid! It was a church group and he wanted to report to the vicar which I told him not to - wish I'd let him now!!
Actually now I'd have called them a bunch of insufferable snobs I wouldn't want anything to do with anyway and walked away head high...but with age comes confidence the skill of being a couldn't care less gobshite
I bf dd initially but had to switch to ff around 10 months. All my friends and family have done a variety of feeding methods, which nappies they used, whether they used dummies or co-slept etc... never judged any of them for such choices it's whatever works for you and baby.
Bf after a section is HARD it takes longer for milk to kick in and build supply for a number of reasons. Something I didn't learn until later. I just was bloody minded about everything I wanted to do! Except I'd have liked to be able to express but unfortunately I never got more than a dribble!
I had a big baby too but a girl so not quite as big as yours at over 9lbs which may not sound huge but both me and her dad are "petite" or at least I was then!
certainly height wise, I'm 5'2" he's only 5'5"! Dd is over 6 ft and hasn't stopped growing yet! We learned MUCH later this is one of the factors of her disability that is genetic but wasn't dx till she was much older.
A friend of mine used to get comments about her big baby as she's teeny and he was nearly 12lbs! Her husband/baby's father is HUGE as is all his family inc the women, dad is 6'10" and built like a brick outhouse!
so then when people met dad after meeting baby they were like "ok now I get it" said baby now 20 and towers over his mum but she still puts him in his place when needed 

Night feeding is tough WHATEVER the method! Quite honestly I found ff at night the worst! Total pita! All the different feeding methods have pros and cons
It's an absolute bloody myth that all formula fed babies sleep through the night.
Yep! I've cared for TONS of babies inc overnights (ex nanny and childminder too) it's total nonsense this myth!
My dd is now a long streak of 21 and doing fine despite not being ebf for 10 years! Also despite the fact she was actually tube fed initially (v poorly when born) and she has plenty of friends - too bloody many!
He didn't sleep through the night till 18 months
Oh god mine didn't sleep through until she bloody started school!
Aren't you worried you'll be hit?
NCT is like the first week in halls of residence all over again
Omg spot on
Honestly op it's their loss - they WILL hit something in their parenting they struggle with at some point and they won't be able to rely on the rest of this group to truly support them I don't think