Scones, I hear you on the shouty mummy thing. I have been reading " how to calm a challenging child" and "happy, easier, calmer parenting" (or something along those lines, I can never remember the order the adjectives go in). I get it while reading, and vow to put it into practice, but then it doesn't quite go to plan and I end up shouting and then feeling even worse than I would do usually because I have failed 
Still, better to read and try, than carry on. Dd1's behaviour has definitely improved overall as a result of my (mostly failed) efforts.
The developmental check for your dd1 sounds a good idea, and it seems as thought they are keen to keep an eye on dd2, which is also good. Glad you saw a good HV.
What are you going to do about the possible depression? I know ADs are scary, but they can make a huge difference. It's an illness, you know, and you wouldn't think twice about taking antibiotics for a chest infection...
Anyway, have some
and
for talking to someone about it all. That is something to be very proud of.