You're not alone. My family treats their last name very preciously, and even though my dad had 5 brothers that would pass it down, those 6 brothers only produced 5 sons, along with 10 daughters. Of those 5 sons, one is married, one is disabled, one is becoming a priest, I'm transgendered, and one is too young to tell. The thought of having only 2 that can pass down the family name worries him (of course, he thinks it's 3, or, I'm not sure. He had a period where he thought for sure I was gay, and pretended to not know that that was,) and it impacts me as well, I feel, as much grief as my family gives me, that I've let them down in this aspect, as well as many other supposed "masculine" activities. I never made the football team in high school, or wrestled, or cared much about anything like hunting or whatever that my dad wanted to get me into.
Hang on, we'll get through this. It'll work itself all out.