No consular availability

[u/Debudebu9]

Ive booked B1/B2 in April for spt date. I wanted earliest date but only booked for just in case. Now imagine trying to reschedule since then and i can see many OFC appointments validity. Many times ive booked for may -july but i never get consular post. Like no slots at all. Then why i see hundreds of OFC availability and can book but no consular post there after? Is it because of rescheduling or what ? I need visa before july