Missed a first milestone

My LO is 7 weeks and my in laws watched him while I went to my 6-week doctor’s appointment last week. He smiled at them for the first time when I was gone. Fortunately they caught a photo of it but I can’t help but feel sad that I missed this milestone. Especially since he will be going to daycare full time starting at 16 weeks and I’m sure I’ll likely miss other milestones like first words and first steps. I also feel like he hasn’t smiled at me since then. I have done about 75% of the child care since my husband went back to work after 2 weeks (and I’m EBF) so it just makes me feel like I’m doing something wrong if he won’t smile at me yet :( I have some post partum anxiety so I'm worried that he isn't smiling at me because I probably have a concerned/worried face half of the time he is looking at me.