Firstly just want to say how sorry I am for your loss... It's such a difficult time to be going through, but try and be kind to yourself and be reassured that sad days are a normal part of it.
It's been just over 6 weeks since my mc, and although I generally feel like I'm doing a bit better now I still have 'down days' Even when I'm having a good day the odd bad half our or so will sometimes creep in. For me I am finding it extremely difficult being around babies or pregnant women, as for now, it is still too painful a reminder of what could have been. I know that in time this will get easier though. I think it's important not to get frustrated or angry with yourself for having an off day, and to keep reminding yourself that it is normal and understandable but that in time things will get easier.
I have also just finished my first period and for me I can say that it wasn't as bad as I was expecting. Slightly heavier than normal, and a bit more crampy than usual but nothing to stop me doing things as normal. Initially I was quite upset as it was a reminder that I wasn't actually pregnant, but that then changed to reassurance that things were actually getting back to normal. I know that everyone is different and therefore have a different experience when their first period arrives but just thought I would share how it was for me.
Hopefully tomorrow is a better day for you xx