First of all, Nerherland dwarfs varies a bit in size. 2.5 lb is probably the ideal weight for a show Nethie doe. Not all Nethies are true dwarfs, many lack the dwarfism gene and they get a bit bigger than their siblings that have the dwarfism gene. But they still don’t get huge.
Second, it’s pretty difficult to get an accurate reading with the method you used. Most scales for humans aren’t super-accurate, that’s why you should always use the same scales when you weigh yourself or you won’t know if you’ve gained or lost weight.
For weighing my bun, I use digital kitchen scales. I put him in a plastic bowl. I first put the bowl on the scales, then turn on the scales and it deducts the weight of the bowl automatically. I then put Bam in the bowl. Then I always write down his weight, because I always forget if I don’t.
If a bun is overweight is sth you see and feel. A bun is supposed to be droplet-shapes seen from above. It shouldn’t have a roll of fat under its chin at 4 months, but does can get such a roll as they mature. I’ll see if I can find a link to a web page that has pictures.
http://www.therabbithouse.com/diet/rabbit-weight.asp