I'm certainly no hair expert, but I've had struggles with hating my hair almost my whole life. My hair and I are getting along better now, so here's what I use:
1st, I rarely wash it. Once a week at most. I'll rinse it more often than that, but not washing it actually keeps it healthier. When I do wash it, I use Nature's Gate shampoo and conditioner (I use the pomegranate one which is supposed to be for dyed hair, but works well for any hair. I would not advise using the tea tree oil one, though -- I think tea tree oil dries hair out).
One strange thing you can do to add volume is put salt water into a spray bottle and spray your hair with it. It'll seem like you've just been to the beach, but it can make your hair look really pretty. TBH, I sometimes am lazy and when I take a bath in epsom salts I just dunk my hair in it and call it a day. See -- not a hair expert, but these things surprisingly work for me.
But really, the most important things you can do are avoid shampoos that contain a lot of alcohol (meaning any cheap drugstore or non-vegan shampoos) and use lots of conditioner. I'm sure you know this stuff, though.
I also learned a lot from a community on Livejournal, strangely enough. I don't know how active it is these days, but you might find some useful info there:
http://longhair.livejournal.com/profileFinally, you may want to experiment with different types of mousse. I used to use Herbal Essences for extreme volume when I was cosplaying, but now that I am boycotting P&G I pretty much stick to organic hairsprays and wigs.
Anyway, I also want to add that I am super jealous of how pretty your hair is, so maybe you should just disregard all of my advise and keep doing whatever you're already doing. ;P
::Edit:: Oh, also, I wash my hair at night, then go straight to bed on wet hair. I know a lot of people don't like doing this, but approximately 1 in 10 days I wake up and my hair has become absolutely fabulous overnight. I just get up and it's already amazing, like magic. Of course, there's no way to control this, and I think I get the curl and body because I toss and turn all night long, thus curling the wet hair in the process.
![Wink ;)](https://mlparena.com/Smileys/default/wink_001.gif)
Yeah, I know my methods are super weird.