Hey Bubs don't blame yourself like that. Don't worry about writing lots sometimes it's good to get things off your chest. There also seems to be so much pressure on us to go out to groups etc when they're tiny. Most of those toddler groups they just bicker over the biggest car or whatever while the mums chat. (or I remember a big kind of swarm of crying babies at a baby group think they'd much rather not have been there!) I reckon they're more for mums really, children only really start to play together coming up to 2.5/3 anyway so don't think that. Btw that is classic of depression to blame yourself completely for something. I had some CBT for anxiety / depression in the past and it helps you challenge that kind of thinking and move on, maybe it might be helpful...another thing I found helped was to think of lovely things you have done, eg giving him a hug in the morning...even when having a bad day there will be something. Just getting through the day with two little ones and battling with bipolar- that's such a challenge and an achievement to even start to deal with...doing your signs, what a lovely caring mum you are, see. You sound like a kind mum, some mums are not very nice to their children are they and even blame them for not being ideal/perfect/naughty/whatever..
On a tangent but did hear that there is some new combination with fluoxetine (prozac) to help with bipolar. As a teenager at uni i was under a huge amount of stress due to a family situation and had prozac for a while, it really helped and found didn't have many side effects and stopping it was not a prob either. It seems to be better than some other antidepressents. Thought I'd just mention that.
I also feel bad (but trying not to) for not going out to a baby signing class or whatever but just having the school run, after that when my ds2 was a baby he just wanted to feed then and that was the morning really. I even feel guilty for listening to the radio loads and while feeding as read somewhere background speech like that is not good. he used to feed for ages and Ilistened to women's hr..
Anyway also wanted to mention was reading 'raising boys' lately it mentioned boys have a testosterone boost around age three, it actually doubles, then thankfully (!) goes down again about 4/5, it means boys can get very active sometimes aggressive around that age my health visitor told me to try get them active, cycle, run abiut as much as poss.. 'walk them like a dog each day' 
she said, not easy if you had a newborn like I had, or you can't get out. Just wondered if that might explain the compliance / formal situations / confined spaces thing. But just wanted to mention it and that it passes. My older boy is like that too, with the gadgets/electrics, dad is an electrical engineer and they spend loads of time wiring things..might just mean your ds is pretty smart that way/logical/good concentration. My dp was slow linguistically as a child and slow to read but loved building things and electrics and now has got a phD in that area, maybe your ds will be the same.. sorry this is getting long too ..
Luci yes I get sick of the 'pointing and paddying' combination we have he just points and that starts tantruming when i get the 'wrong thing' eg cup...I have to say show me all the time then carry him to where he points. It;s worse as you know how they can be picky, just now it was the wrong colour spoon.. I have heard there are long waiting lists for these things, my ds is shy and avoids eye contact with new people too, I know he's confident usually though, that sounds normal don't you think?
I had a call from the speech therapy people at lunchtime asking me if I wanted a place on a Makaton signing course tomorrow morning. A bit last minute and isn't a nursery day for ds, and can't take him along, so no to that one.