sure there are, there are always pan-disability groups somewhere, it's just digging them out. (although have noticed the 'trendy' support groups - currently children with diabetes in our area) getting a lot of press. obviously a needed service though, but depressing if you have a child with a different issue. sure start would be a good place to start though - and if there isn't a group for teenies, pop in and ask them to start one. i bet other mums will come out of the woodwork. if there are really none, contact the leaders of the (specialist) groups that exist and ask if you can come along. dd babies can share a lot of the issues of other disabilities inc downs, and really it would just provide a space for you to have a cup of tea with parents going through similar fears.
whereabouts are you? the other thing i used to do is loiter meaningfully when i spotted other tots waiting to see developmental paed/ physio etc, and strike up converstations. ask your physio if she sees any other lonely mums that might be interested in coffee, and ask her to pass on your details.
in the near future, you need to ask your physio to supply some more supportive seating so that you can try some different activities (sometimes they will do this, sometimes will refer to OT - depends on area). at this point a bouncy chair should be fine, and you can prop as necessary with rolled towels. usually they offer a 'tumbleform' or one of the jenx chairs first, but it can vary, depending on where you are. personally i love the tumbleforms, as you can alter the angle with the velcro to get different levels of upright lol. they are also useful for feeding etc once ypu establish solids (not sure where/ if you are onto that).
the mouthing thing is tricksy. dd2 couldn't get her hands to her mouth, so we essentially had to provide mouthing expereinces for her, either by gently encouraging a bend in the arm and holding it so that she was able to get her knuckles in, or by hand over hand holding a teething ring for the same purpose. she didn't ever really mouth anything except her knuckles really, so we spent a good deal of time holding them in the right position! really important for later development that this opportunity is provided.
and don't forget the toy library! the sn section is your friend! elc used to do a really lighweight shaker with a pencil thin handle - we used to wrap dd2's hand around it and hold it hand over hand to shake. your physio can give you some ideas about positioning to make some things easier, and often can give you some more equipment (lol) - we had a wedge and a gym ball for different positioning and exercises, which can also be used to encourage/ aid some sort of play. once dd2 was able to make some sort of intentional movement with her arm (a sort of wave lol) we made the most of it - those shakers that you can wrap round their wrists/ ankles are good. essentially you sort of go 'back' to the toys that are designed for younger babies and work out how you can adapt them to your child's abilities (often essentially you playing with them to stimulate attention lol, but you have to start somewhere)
i hope i'm not sounding too lecturey - as i said, the first year is really very hard, but there are lots of things you can do. it's hard sometimes to realise how much you are doing, and notice tiny glimmers of development. our paed was always very positive about noticing improvements between appointments, however subtle - sometimes we need to step back a bit to really see change.
is he smiling yet? dd2 finally smiled at about 6 months - i was blown away and had given up all hope. it was very difficult to keep up stimulating activities etc when there was no facial reaction at all - sort of 'why am i bothering', but it was so worth it!