Is it true you stop growing 2 years after your first period?

Nope, not true at all.

You continue to grow throughout puberty, until around the age of 18 years old, menarche is just one of many things in your body that change as you go through puberty and these different aspects of puberty (menarche, breast development, body hair, hip size, height, etc.) aren't directly related to each other: everyone develops differently.

If you stopped growing two years after menarche everyone would be short, consider it's normal for girls to reach menarche from as young as 10 years old, Lina Medina (the worlds youngest mother) reached menarche when she was just 8 months old...she grew to be a perfectly normal sized woman, not stuck at the height she was at 2-3 years old!

Three years. It's just a general rule of thumb and every girl is different. I grew two more inches five years after.

no it's not true because if it was all girls would be short