Growth scan at 33 weeks??

Jesse
I just went to my 24 week and 5 days scan on Wednesday and he is measuring around 1 lb 10oz. I'm now 25 weeks and they said I have to go back in 8 weeks to see growth!!! They asked about Down syndrome and the tests and what was size my other son when he was born... I'm freaking out! They didn't do this with my first son and I only gained a few pounds with him (I'm overweight). What does a growth scan mean?! They measured the fluid around him and didn't say anything about it. This was the scan from 20 weeks