Obi-Wan went over thirty years without a heat. It was hardly unusual or unexpected. Everyone knew omega reproductive systems were finicky. Omegas were incredibly fertile while in heat. Nature had, perhaps, compensated for the situation by ensuring they only went into heat when...conditions were correct. OR, the Dark Side AU where the Empire is already in power, the Jedi are long gone, and Obi-Wan Kenobi ends up leading an army to wipe out the Emperor's enemies. Things get more complicated when he goes into heat.