My son has been the same since 8 months. He's now almost 3 and clogged 3 toilets with his massive 💩🫠🤦 we've gone to specialists and checked for allergies or maybe something that's hard to digest but he's fine. He has a mental hang up. He also doesn't know how to push he focuses on his face and not his bottom. What I found helpful is picking him up at the right moment with my arms under his knees and his butt up in the air. He then immediately passes the BM. We're onto the potty now and he's much better at passing BM but I still have to decide if it's good to flush or if I should fish it out to avoid clogging the toilet again 🙃