If you're only five weeks, you're feeling gas movement in your intestines. You won't have a bump, as your uterus is still behind your pubic bone. You're probably feeling food in your intestines.
Your embryo is only half a centimeter, and barely shows up on an ultrasound.
If your placenta is posterior, you might start feeling movement as early as 13/14 weeks.
You're also probably a little bloated, since the hormones slow down your digestion.
it's probably just gas since the baby is still itty bitty.
I agree. Baby is way too small to feel yet. Also that bump is most likely your uterus. Some women get their bump sooner then others because their uterus grows and pokes out a bit more then others. Especially if you've already had a baby before. First time moms, this typically doesn't happen with. But the baby is too small to show yet also. I didn't show till 6 months with both of mine. Others can start to show around 3-4 months.
Maybe your further along then you think