Hello LiveInThePresent
I have no experience personally with Celexa but I had some time on my hands so did a Drug Safety Data search for you for Celexa (Citalopram). I found a reference to two adverse effect symptoms which may relate to what you are experiencing. Please note these effects were observed during pre-marketing trials of Celexa and were not specifically attributed to the drug.

Briefly they are:
Apathy: frequency - common
Depersonalization: frequency - uncommon

Definition: Common adverse events are those occurring in less than 1/10 but at least 1/100.
Uncommon adverse events are those occurring in less than 1/100 patients but at least 1/1000 patients.

Were you given any safety information on the drug before starting and has you doctor asked you about any side effects during your time taking it?
You're probably aware you should not stop taking it suddenly. If the lack of feelings you mention are concerning you deeply you may want to discuss it with your doctor.
Hope this is of use.