Is it normal to feel fat or weight gain as early as 5-6 weeks?

I feel so self conscious out of a sudden. Last time before ttc I used to run and work out occasionally when I can, but now that I found out I'm pregnant I don't dare to do any impactful exercises - trying to just take walks and yoga stretches. But I feel really untoned and flabby at my arms, thighs and waist, with clothes being tighter that I need to buy new ones. Does anyone experience such slight body change so early during pregnancy? Is it normal?