Not sure what breed our puppy is

My Girlfriend and I adopted our puppy in early April. We adopted him from Animal Care Services but we were never explicitly told what his exact breed was. He has Pit Terrier genes for sure but I don’t think he’s purebred, so me and my Girlfriend constantly go back and forth on what his breed really is. He’s about 5 months old and we got him when he was about 8 weeks old, so his face and body has changed a lot. Any ideas as to his breed?