I feel sad I'm not enjoying my baby

I have a 4 month baby. We just moved 2 weeks ago. I am so tired all the time. I feel like I am floating in time just holding the baby and breastfeeding and putting him to sleep (and keeping him asleep). I'm sad because I feel I'm not enjoying this enough and I should. People say I'll miss this and I'll probably will, so I wish I was able to enjoy it more. Someone told me to tone done expectations and accept that this time is about taking care of the baby. I suppose that should help me enjoy but it's had to be in that state of mind all the time. Any advice or experiences? Thanks!