I would recommend TCM - acupuncture and herbs. When TTC DS it took me 12 months and I had erratic cycles - 14 wks longest, 6 wks shortest.
When I stopped bfeeding af did not return, neither when i came off mini pill. I went the TCM route - got af a week later, then a 30 day cycle and then I got preg the next cycle... highly recommend.
Your GP may also have some answers, it cant hurt to get a few opinions...