I had a 7 month old at the time so that was quite a distraction, I spent a lot of evenings holding sleeping DD and sobbing, hopefully she won't remember! (I tried not to cry if she was awake).
I didn't do any yoga or gym or anything, if anything I probably just ate like a pig and drank a lot of wine to be honest.
I had an overpowering overwhelming urge to be pregnant again as soon as possible and I was so lucky to fall 4 months after my loss, which meant that I lost my son March 2013 and had my living son in May 2014. So now I can sort of rationalise it a bit and think that I wouldn't have my living son if I hadn't lost DS1, as the dates wouldn't have worked (DS1 due 1 September so I obviously couldn't have gone on to have another ny May 2014).
The timing of mine was awful as I had the TFMR on the Saturday and was due to return to work from maternity leave on the Monday so I was working the Monday and Tuesday (I worked from home on the internet so no problems with sobbing at desk), and was busy getting back into a work routine, so that kept me busy.
Basically I remember trying to keep going and just put one foot in front of the other and plod forwards, while crying a lot in the evenings at night, thinking about my loss a lot, and talking on here a lot.
Once I had a clear harmony test with my subsequent pregnancy I think I focussed on that a lot and my baby was very healing really.
Not much help to you I don't think, sorry. It seems like you just need to get through any way you can, it's just so shitty and painful and unfair and that never really goes away.
Mine was 16 weeks same as you, you just assume once you get to 12 weeks you're in the clear don't you.