Baby measuring small

I’m 25 weeks and I’m measuring about a week behind- which didn’t seem too much of an issue with my OB. However, I’ve gone to 2 appointments with MFM to check growth and my baby is only in the 3rd percentile. We have a plan to check weekly (Doppler to check blood flow in umbilical cord) and in 3 weeks another growth check via ultrasound. Anyone else going through this too? I’m trying not to stress about it but I don’t know anyone else that has gone through this or is going through this. Also need to mention I’m 35 so I’m at that “advanced maternal age”.