What a GIFT!!!
I know it hurts that his sperm donor is little more than that, but hey, he is doing you a MONUMENTAL FAVOR when you consider the alternative. You and your son are much better off...
My oldest and my second got their teeth by 4 months of age. My third (who will be 13 tomorrow) got hers a little later, like 6/7 months if memory serves (which is average). And my baby got hers pretty late. She was nearly one year, like 10/11 months when she cut her first teeth.
It's so odd how one remembers such strange details.
I know it seems easy for me to say but just appreciate every day with your son - I know you already do....
HAPPY MOTHER'S DAY a little early ma'am.