At the outset let me clarify that it is difficult to give you exact answers, and the best person to answer your questions is your treating doctor. Conceiving is really a complex process for which numerous factors have to be in sync. It is difficult for me to explain all these as there are volumes of books written on the subject. However:
1. Sometimes, even if the egg is produced, it may not be reaching right size, and as a consequence, one fails to conceive. Sometimes, one gives Siphene empirically, when all other tests are normal.
2. Keeping in mind your cycles of 40 days, I think you have a problem of ovulation. Ovulation does occur occasionally and erratically in women with prolonged cycles, and you may have ovulated in the cycle you were monitored. If the egg membrane does not rupture , pregnancy will not occur, and that follicle goes waste after 14 days.
3. Your doctor may withhold the injection for ovulation this time. I would suggest you just wait and watch what happens to these eggs in this cycle. Normally, one does monitoring with serum estradiol as well, to avoid problem of hyperstimulation of the ovary and its complications.
4. In my opinion you require Siphene and injection for ovulation. But monitoring should be with ultrasound, hormonal monitoring (blood tests) and postcoital test.