So my group has recently had a technomancer join us, but she also wants to be a drone rigger, so we have been trying to figure out if a technomancer can use machine sprites to control drones?

Simple answer. Yes.

Ok thanks our GM kept saying Drones dont count as "devices" like it says in the book

Then your GM is a moron,

There's a table on p. 214 in the main rule book which lists example devices, you might ask your Gm to take a look at it. Drones are specifically listed in there.

You may want her to look at the Dronomancer Stream.