Hello and welcome to HCM Since, you have had two children, the possibility of infertility is ruled out in your case. Inability to conceive even after staying together for over an year and following the ovulation calender definitely requires further work up. Firstly it is imporatnt to know the functioning of the endometrium. So, you need to get an endometrial biopsy done wherein a piece of endometrium is taken and examined under the microscope to look for the phase any dysfunction. The endometrial biopsy is taken during the second half of the menstrual phase. Secondily, get a follicular tract done. This investigation will allow the examiner to see the development of follicles on different days of the ovulation cycle. Thanks and take care Dr Shailja P Wahal