Hi jakey, I am about the same age as you, and one baby who is nearly 2, conceived instantly. Bf her until early November but it was down to once a day in the evening (and the odd 3am feed...). Periods came back when she was nearly one. TTC since April/May. Periods were regular, appearing on day 27, just as before DD.
In late Sept, after 6 cycles, I went to the GP. Surprisingly, perhaps, given I was bfing, 35 and had a DD conceived first cycle, she ordered blood tests at day 3 and day 21, and a scan. Scan was perfectly normal. The day 21 tests indicated I was not OVing, but I am fairly sure that was because the cycle was unusually long that month, unhelpfully. However, I wanted more answers when the blood tests were unusual, and the GP didnt seem to know, so I paid to see a consultant in November. £200 and an appointment the same week. GP wrongly assured me that Bfing would make no difference as I have regular periods and was once a day.
Consultant is quite an eminent chap, runs an IVF clinic, seems to know his stuff. Anyway, he took one look at the day 3 results and said a) he thought I was ovulating, and b) he could see I had very low FSH levels. Low FSH is a good sign because it gets high when you are peri menopausal.Low is caused by excessive exercise, being underweight or bfing. With me, he was confident it was recent bfing as I am normal weight and don't exercise too much.
A couple of months on, I've stopped bfing but still leak milk occasionally (I always had lots and carried on bfing even when working FT hours). He has suggested I leave it a bit then have some scans through the cycle to check when OV is happening. I cling on to the words in the letter that say there is a good chance of conceiving without assistance now bfing has ceased. fingers crossed. good luck. x