Clothing Rigging Problem! Please Help

Hi! I’ve been using Blender for 2 years now and this is the first time I’ve encountered this problem.
I’m trying to rig this t-shirt onto the body of the character, I’ve tried to do so by manually choosing the data transfer modifier and also by “Transfer Weights” in weight mode but the mesh appears offset. I’m adding a picture so you can see the problem here. Can somebody help me? Thanks xx

It doesn’t look like your shirt is in the same rest pose as your character (t-pose vs. a-pose.) Model it into the same pose of your character before data transferring or armature deforming.