My son may not be properly potty trained in time for school.?

I am having a time trying to potty train my 2 year old, who will turn 3 in August. He has to start school in September and I am not succeeding in my endeavour to have him potty ready. This is a requirement of the pre-school. So far I have gotten him to master No. 1 but No. 2 is a real trial. I have even tried keeping him out of his diaper and he showed me that he could hold it for as long as two days. He specifically asks for his diaper and once he has it he will go (no. 2) immediately, but runs to the toilet when he has to urinate. He seems afraid of the mess, not the toilet. I have looked up every article online and tried everything they suggested without luck. Can someone advise me what else I can do? I think I am going crazy here and since I want him to go out this year and not get kept back, time is running out.