Nervous-advice please?

Laura
So, I had a growth scan at 31w6d, and they discovered that my placenta was already at a grade III (aka an "older looking placenta", meaning the placenta appears older than the baby) apparently placentas are only good for so long, and they reach full maturation around 38 weeks- that is when it's supposed to reach a grade 3. They want me to go back in for another ultrasound at 36 weeks to make sure the placenta is still working properly. I'm so scared it's going to stop and not feed the baby before 36 weeks- I'm 33 weeks now so I have to wait another 3 weeks for the u/s. Anyone else experience this? I feel like I'm being so paranoid but in don't think I feel him moving as much.. But in paying much more attention to his movements now than I was before.. I'm so stressed out about it!