Weight gain & a little bit more

So similar to the title out of curiosity, pls excuse if ive put this in the incorrect forum :(
Im currently at 8 weeks and am already showing and also put on approx5-6 kg in the last 3 weeks which for me has never happened before, also with the severe morning sickness i am quiet suprised,this is my 5th child so im putting it down to this being the reason. I do know the more pregnancies the chances of showing earlier on are more common but i mean i look like im 4 months pregnant..
Secondly my little girl who is 3 at the moment keeps telling me mum my babies are growing, when i ask her why babies its a baby she keeps saying no mum theres 2, freaking me out a little.
So my question is those with multiple births have you ever experienced this and has your other children ever been correct on their intuition?
Also with the weight gain, anyone else gained this much so quick?
My diets the same nothing has changed at all.
Thanks in advance!
Looking forward to your replies

I am certainly an early show-er.
I'm a size 8-10.
With my first pregnancy I had a little bump at 8 weeks.. Then with second I had a weeny one at 6 weeks. Third by 5 weeks, 4th right on 4 weeks and 5th / current 4.5 weeks. Yet I have friends who didn't show until 20 weeks. We're all different.
As for the weight gain, that does seem a lot in a small time frame so early on.. Have u just been so hungry? Eating wrong stuff? Or it's coming on regardless?
I can't really help there as only one of my pregnancies went beyond 23 weeks..

I have had a twin pregnancy but it did not result in any babies but I can relate to the weigh gain and looking pregnant.

I've always been able to hide it except for this time. I have 3 cysts however with the largest been the size of a cricket ball and two around the size of golf balls. So I am putting that as the reason as to why I look pregnant when I am only 8 weeks along. I don't think I look any more pregnant now than I did 2 weeks ago.

Have you got a scan booked to do a head count?