He wont sleep past 4:30am

Its killing me. He's 14 months old and has been doing this for a few months. I have tried everything but this child will not sleep longer. He refuses to nap in the morning so hes up from 4:30-12:30/1pm. He only naps for an hour max then is up until bedtime at 8. I've tried forcing the morning nap, giving him quiet time in his crib instead of the nap, moving bedtime up, moving bedtime back. In the morning I've tried rocking him back to sleep which results in a massive tantrum, consoling him in his crib and leaving again, consoling him in his crib and sitting in his room for some time before I pick him up, not consoling and sitting in his room before picking him up, not going in his room and interval crying. I've even tried to just let him cry but nothing is working. I hate fighting with him every morning, it just sets us up for a whiny day. I'm 33 weeks pregnant with my 2nd and I need to get this corrected, I dont want to deal with this when I also have a newborn crying to nurse. My goal is at least 6am, 7 would be amazing but I know it is probably never going to happen. I'm at a loss and I'm exhausted, the 2 cups of coffee I have a day is not cutting it and I cant have any more. If anyone has any ideas I'm desperate enough to try anything at this point.