See for example: http://www.nature.com/news/reproductive-biology-fertile-mind...
> in 2009, Ji Wu at Shanghai Jiao Tong University in China and her colleagues reported that they had isolated from mice what she called “female germline stem cells” — not from bone marrow, but from ovarian tissue. When her team transplanted the cells into chemotherapy-treated female mice, they developed into mature oocytes, then fertilizable eggs and, the clincher, healthy pups.
>[Tilly] has since published a parade of headline-grabbing papers, culminating this year in a report2 that he had isolated the elusive stem cells from human ovaries and coaxed them to develop into bona fide oocytes. But his work has been dogged by doubt.
It's still really messy and I haven't heard anything new in 3 years, but humans may have the capability in place to create unlimited oocytes like sperm, it's just hard to tell why we don't (the OP's story is one story - there are unlimited possible stories, including simply random loss).