@s14a sorry you're so anxious, I'm your sister in this regard.
The symptoms you describe right now are bang on exactly right for your date, tiredness, nausea, gas you have symptoms and they don't have to be constant or extreme.
When I had the MMC it was only after I realised that for the previous 2 weeks I hadn't had symtoms, I was carefree and confident and so naive.
I'm 10w+4 now and just had a great scan today, this is my 5th scan, yes 5th. I've had symptoms but convinced myself they afford strong enough, I got nausea for just over a week and it went away last week so I was tortured with anxiety.
My advice would be this, every day I felt my boobs, I really mean my nips haha if I had a sensation at all, even mild I counted that as a good sign, my boobs went completely dead with the MMC so any feeling is good. Not saying first you to do this exactly, but fine something that you can do every day that contents you.
I would go ahead now and register with midwife, just grit your teeth, do it and forget about it.
Be thankful every day that you're still pregnant and now you're 8 weeks maybe ring epu and ask for an early scan, they may give you one.
Saying don't be anxious is silly, you're going to be anxious but try and rationalise every day, this is a new pregnancy, new outcome and the chances of a successful pregnancy are higher than an unsuccessful
Get that midwife booked, just get it done and see how you feel after x let us know how you get on x