Keen to conceive. Cause of infertility?

Hi, me and my husband are trying to convince from last 1n 1/2 years .last year Feb I had a miscarriage (after 5weeks) it was later found to be a chemical pregnancy by docs as der was no foetus seen in sonography dat time . Recently i consulted a gynaecologist . After seeing my case she recommended to take ecosprin 75 n fertisure F to me n have asked me get AMH, TSH n Prolactin test on day 2nd of periods. Which I did n results are normal. Other than dis she also have asked to get a X-ray HSG . Now my concern is it really necessary to get X-ray HSG done.... I mean if I have blocked tubes how would I have conceived last year for 5 weeks?... also last time my sonography was done on 7th day of period in which endometrium was found to be 4 mm is it a concern. My husbands semen analysis (count n motility) is normal. What could be the cause of infertility?? Just want to confirm if x-ray HSG really necessary in my case . Thanks