Every month I get upset :(

I have been with my partner 12 years and for 10 of those years have never used protection. In 2012 we underwent ivf (icsi) after finding out my partner had a low sperm count just 1 million!! And we were blessed with a beautiful little girl is is almost 4. Although I'm extremely lucky and count my blessings every day that I have my little best friend I can't help but want her to have a sibling:( and with ivf being so expensive we just can't afford it again. We had a little good news about 4 months ago that my partners semen has increased to 10 million!! But still a low County and although I know we cannot conceive naturally I get my hopes up every single month :(