you are mistaken the dwarves are the other short race who are supposed to be associated with something really big.
At least for D&D in the core books, I'm a bit befuddled as to how I'm mistaken.
Dwarves at 4' and 150 lbs feels different than Gnomes at 3' and 60 pounds, even if they are both described as small for a sizes category in 1e. However in 2e, Hill Dwarves are S to M, and Mountain Dwarves are M. The Gnomes are S and the Dwarves are M in all the later editions.
Notably, the 1e MM describes Dwarves as being the larger cousins of Gnomes (a similar relationship is noted in B, 1e PHB, 2e PHB and 2e MM).
In 3.5 PHB and MM the relationship between Dwarves and Gnomes isn't given but they are Medium and Small respctively.
In the 4e PHBI race entry, is the Dwarves "proudly proclaiming they were made from the earth itself", "honor long-dead clan founders", and "revere Moradin as their creator" reminiscent of their Tolkienien origin? It mentions they once labored as the Giants slaves but not of another relationship to them, and they are again medium. In the 4e PhB II race entry the gnome is again small (smaller than Halflings) , but we get the big change to being from the Feywild and resembling Elves and Eladrin.
5e has no relationship with the other races noted in the PhB for Gnomes and has them listed as Small. Given 5e's seeming tendency to respect all earlier editions if possible, one may speculate Forest Gnome picks up the 4e relation with Elves and Rock Gnome the earlier relationship with Dwarves. Anway, Dwarves are again medium with nothing in the PHB about being a small version of anything, and Gnomes are small.