HSG vs. saline test

Alison, 🌈 👶🏻 born 7/26/19

So we had our second miscarriage in April - first one was in December. Both times in first trimester and I don’t have any living children. So with my age (39) I got referred to an RE to do testing. Today I did an HSG which I was very nervous about it but all went well I had hardly any cramping or bleeding and the doc said my uterus and everything was totally normal, tubes open, no polyps etc. my question though is I’ve also heard of the saline infusion and am also wondering if I should request that test as well. Does anyone know what the difference are Between these two? I heard the saline one looks more at the ovaries and for cysts. I just want to make sure i cover all my bases and do any and all necessary testing Bc knowledge is power and even if they never find anything wrong (which is ideal) it still will give me peace of mind! Has anyone ever had an HSG and then also did the saline or did the saline and then HSG?? Thanks!!