How small is too small at 32 weeks?

I had my growth scan today as my stomach was Measuring small.

I am 32 weeks + 2 and today she is weighing about 1.5kg or 3.5lbs.

The fetal chart on Google says she should weigh 3.7lbs at 32 weeks, I don't know if it's a major problem that she's around a couple hundred grams smaller, but with babies it all counts.

US Tech called the midwife and asked if they wanted to see me today instead of tomorrow and they said tomorrow is fine but changed my appointment from 3pm to 8am so it wasn't an emergency as such.

All her measurements are fine and her organs are good.

I don't know if I should be majorly concerned right now, I am a bit stressed for obvious reason, but I don't know how else to feel.

I don't know what I'm doing wrong for her to be so small. I started out at 55kg and I weigh 71kg now this far in, so I'm not under eating. I dont think she has a problem inside her body as all the US Techs say it's all fine and looks healthy. I don't know :(