My hips started expanding around 8 weeks. And only elastic waisted things fit me at that point. I was fully in maternity clothes by 12 weeks. You also could have bloating, gas and bowel distension, all very normal in a healthy, normal pregnancy.
Also, I only briefly had nausea (and very mild at that). It lasted a week at most. I generally say I had no morning sickness. I hate hate hate that they tell you something could be wrong because of that! While it's true that in our culture, where morning sickness is the norm, that there is a slightly higher miscarriage rate among women who don't experience it, in some cultures morning sickness is rare. The fact that you're having some nausea indicates a well and properly implanted embryo.
You probably can see a practitioner if you want. An early ultrasound might help calm your fears and in this case, the benefit (relaxed mommy) might outweigh the risks. Also, you could have your blood drawn to see how much hcg is in your system, if the numbers are in the normal range that might reassure you too.