In our family, elders say to look at the belly shape to guess things, but actually only the doctor's ultrasound can tell you if baby is growing fine. I always trusted my gynac's measurements during my checkups. Don't stress about measuring it at home.
Oh sweetie, don't obsess over the tape measurements! Every belly grows differently and your body is doing such a beautiful job growing a miracle. I used to cry seeing others with big bumps, but my baby was born perfectly healthy.
Honestly, your doctor will measure the fundal height from your pubic bone during checkups. I had a C-section and my belly took a long time to heal and go back, so just trust your gynac's measurements and don't try to do it yourself at home.
Just stay positive and don't compare your bump with others, dear. God has a unique way of creating each life, so keep your mind peaceful. Let the doctors do the measurements while you focus on eating well.