I think your questions--ie, whether you are experiencing a relapse, whether the medication or the depression (or both) causes apathy--are good ones. I have a few thoughts.

First, you mentioned that you were unable to cry at your mother's funeral. In order to know whether the medication blunted your emotions, you would need to know whether you had experienced any emotional blunting before your mother's death while on the meds. If not, then it's possible that the medication was not the reason; perhaps, for example, the grief was too intense and you suppressed it and/or you began to fall into a depression. Either of those things could have made you feel apathetic. In that case, you may have actually needed to increase your dose instead of taper off, or get into therapy, or both.

Similarly, in trying to figure out whether you are experiencing medication withdrawal or a relapse of your depression, you should think back to prior depressive episodes and see if the symptoms were similar to what you're experiencing now.

It's possible that you are experiencing both withdrawal from the meds and relapse. When I tapered off of sertraline a few years back, I experienced both withdrawal and relapse. I'm sure that part of it was withdrawal because I experienced symptoms such as dizziness and nausea that I had never experienced before during episodes of depression or intense anxiety. And I'm sure that part of it was relapse because once those symptoms passed, I experienced symptoms that I was very familiar with from prior episodes of depression, and those symptoms lasted a very long time. Also, I was dealing with a series of stressful situations that were very similar to the ones that had triggered depressive episodes in the past.

If I were you, I would get into therapy and then discuss the possibility of restarting meds. I would also let the therapist know about my concerns with emotional blunting. Perhaps a different SSRI would work better, or perhaps the dose needs to be adjusted. Or maybe you're just going through a depression and need to work through it with the therapist.

Hope this is helpful.