How do I deal with recurrent doubt about the number of rakats? Should I base my decision on what I predominantly think, or on the higher number? And do I have to perform the prostration of forgetfulness (sujood as-sahw) in both cases?

Maliki jurists hold that for one who is frequently afflicted by misgivings (al-mustankah), the predominance of assumption (ghalabat al-ẓann) and doubt (al-shakk) are the same. Such a person should build upon the greater number unless certainty is reached. Doubt, in their terminology, includes both assumption and delusion (al-wahm). Accordingly, as long as the questioner is frequently afflicted by misgivings, she must build upon the greater number, even with the predominance of assumption. Jurists advise one who is frequently afflicted by misgivings to turn away from obsessive thoughts, as pursuing them can corrupt the religion at its very foundation.