Problem w/ images on subdomain

I started hosting my images on a subdomain to have my site load faster. The problem I’m running into is if I try to upload an image from the server, WordPress isn’t recognizing it.

It’s still looking in the uploads folder. I’ve put in a redirect for the subdomain that all of the images I used previously are loading fine. However, I’m wondering if anyone can help me with this issue for any new images because I generally store a large and smaller version of each image.

Is there another redirect I need to add? Another way to upload from the server? I’d appreciate any input someone could offer. Thanks.