Feeling conflicted... anyone else?

I'll be 30 weeks tomorrow with my daughter, our second baby. I am so excited to meet her and have a family of 4. But I also feel sad about losing what we have now with our family of 3. My son will be just under 2 when our daughter is born and I love him like crazy and we gave so much special time together as a little family where we can really focus on him and I feel like I'm going to miss that. I know nothing is going to change: my love for him, his love for us, his adorable smile, infectious laugh, and big personality, but I guess I just worry that I won't get to soak up every moment of it like I can now that it's just us. Anyone else feel this way? Any experienced 2nd time moms have advice?