Fundal height means and tells very little. It's not uncommon to measure off. Babies size, position, your weight gain, the person measuring, and your fluid amount all influence this. For example, when I was 33 weeks my fundal height was 27 cm. Ultrasound showed my daughter was growing perfectly fine. When she was born at 39 weeks she was 6 pounds, 12 ounces and 20 inches long. I wouldn't worry about it too much.
My fundal height was consistently measuring 2 CM off my whole pregnancy.. Then at 30 weeks, I was measuring 3 1/2 CM off.. my doctor started to get concerned and said I would need a growth ultrasound after my next prenatal if the discrepancy was more than 4 CM off... I ended up in the hospital befpre that and I had a fetal assessment ultrasounds anyways and sure enough I was measuring 31 weeks exactly at that point.... Since then I have been measuring about 5 CM off... I think at my 35 week appointmne, I was measuring around 30 CM... My doctor said she was not concerned about it anymore because I was off before and my growth scan was normal.. As well, my baby has dropped so that automatically throws fundal height off...
I wouldnt stress yourself out about it too much, if your midwife was concerned she would have said something.. but there are a ton of reasons that FH can be off..
thanks for your reply it would be a big for me