Script to resize and rename images to multiple file sizes in Photoshop CC

I have THOUSANDS of images I have to do this to:

Resize to 500x500 and rename to FILENAME_MD.jpg

Resize to 374x498 and rename to FILENAME_SM.jpg

Resize to 276x385 and rename to FILENAME_XS.jpg

My process:

I have to separate the Portrait size vs Landscape sizes so when I resize them to 374x498 and 276x385 the images won't get cut off

I tried just trimming the original 2000x2000 and then creating the droplets, but for some reason some of them kept getting cut off, so I am now just eyeballing them and separating them out. (Please tell me there is a better way!)

Here's what my folders/droplets look like:

There has GOT to be a better way of doing this!!!! Please someone help!!!!! I have 50,000 images to do this to!