Hi @DTyshetskyy,
I think you’ve done most of the job there.
You’re probably missing this simple thing : specify the list of properties you’d like to receive.
Have a look at the custom objects endpoint, when using the GET you need to add, as a query parameter, the list of properties you want the call to return :
Try to do the same for your your custom object records and you should get there!
Hope this helps !
If it does, please consider marking this answer as a solution 
Best,
Ludwig