I am 6 weeks pregnant. The pregnancy was a bit of a shock. Started with a new job three months before, and is our second pregnancy. So I had mixed feelings about it. Did not inform work yet, want to se gynae first.

Appointment was scheduled at 8 weeks pregnancy.

Over the weekend of the 6th week, I had a glass of dry white wine, diluted 50:50 with soda water. That everning I had stomach cramps, was bloated and had a lot of gas. When I went to the bathroom for a bowel movement there was a lot of bright red blood, enough to use a tampon during the night. The next morning when I removed the tampon, it was soaked. But after that the bleeding seized completely. I am a smoker, but cut down a lot on my smoking. We used crystal meth and methcathionone on 2 occasions during the pregnancy. The crystal meth was just before the 4th week, and the methcathionone after the bleeding, as I thought I had miscarriaged.
Did I miscarry, and if not, what effect will the drug use have on my baby? Still not sure if I want to risk losing my job by pregnancy.
And very moody, had a lot of stress during these 6 weeks, my husband and I fought constantly.

I had upper respiratory tract infection during the 4th week of pregnancy, with a very high fever, as well as fever induced nightmares of losing the baby. The doctor prescibed ocilocilum and Lacobiotal, which I used for 2 weeks (week 5-6).

We can't know if you miscarried. The fetus would have been big enough to be seen unless it was in with feces and blood, possibly, and you weren't actually inspecting what was in the toilet. But it sounds reasonably likely.
I think you should address smoking, legal drug, and especially meth use with your doctor when you know if you are pregnant or not, and assume that you will stop until you find out - even if you decide to abort. Obviously meth is known to have an effect on a fetus, but how much for 2 uses in the first month is just too difficult to research, and is based on probabilities anyway (you could fall into the higher % or the lower % of any given birth defect). You can wade through all the studies online.