I’m so sorry about your daughter.
This could be partly an anniversary reaction, where your depression and grief are resurfacing as an annual reprise around the time of the accident. It happens often for many people.
Or, it could be that the reality of her being gone is hitting you at a new level, because perhaps you’re more connected to your feelings about her absence now. Additionally, there may be other losses that this loss is tying into now, or other life events that you would have wanted her to participate in.. lots of poignant possibilities for why now. This is a profound loss and it will tend to revisit you, sometimes when you least expect it to. There is certainly nothing weird or abnormal about it.
But, as you say, the point is more to try and figure out what might be useful to you at this time, not so much analyzing why.
I would suggest you find somebody neutral and compassionate to talk to about this - a wise new friend, a counselor or a support group. Especially because you were dissociated at the time of her death, you may still need the space and time to process it, reflect on it, feel your feelings about it and integrate it into your life as you live it now.
Trying out some expressive arts, such as journaling, artwork, music or poetry might be very helpful, too. Sometimes you can work through hugely impactful losses more effectively via these more right brain avenues, rather than just talking about them.
Regular, aerobic exercise may be one very good, mechanical way to get your energy moving again - depression is all about blocked energy, when all is said and done.
I would also recommend our guided imagery for Grief, for Depression and for Posttraumatic Stress. Especially the Grief and PTSD imagery will help elicit your feelings and simultaneously provide comfort. It may be time for this.
If you find that nothing is helping and the depression is still the same or worse, you may want to see about trying some temporary medication to get you off the dime and get you going again.
Best of luck and, again, please accept my condolences.