Breast feeding !

Did any of you TTC while breast feeding ? My son is almost 8 months . And I've had two periods since he was born one in September and one in January . It causes them to be very irregular . So I never know what to expect . If correct I should start today . But yet nothing . I haven't tested today but yesterday I got a negative . I was really hoping everything was getting back to normal . But I guess not . Have any of you had any success conceiving while breast feeding . I think I'm fixing to work on weaning him . I just feel so guilty and selfish knowing I'm doing it so we can get pregnant again . But I've done it a long time and we've been talking about baby number two since William was two weeks old . Just didn't expect it to be this hard to get pregnant , we weren't trying for baby number one and it happened very quickly so I'm getting discouraged .