Hi Vivid,
I think it's perfectly normal. I had major mood swings while I was still 'out there' which continued for quite some time into recovery. I feel much more stable mentally, today, but that can change. I've had meltdowns in the car, not unlike the one you described.
I take meds for my depression, but I've gone without (both before and during sobriety) and didn't do well. Everyone is different, though. Just because you are having mood swings, doesn't mean you are depressed. There are many useful tools online to help you diagnose yourself i.e. questionnaires etc.
I am like you in that I can be highly motivated when trying new things, but I can quickly lose interest or the drive to continue if I don't see quick results. I guess that's just the addict in me - I am not used to working hard for results, and that's been a blessing and a curse.
Today I need to be satisfied with being less than perfect. That means I'm no longer a size 6, my house usually needs to be cleaned, and I make a lot of mistakes in life.
The single most thing that has helped me in sobriety is being accepting of myself, just as I am, just where I am at today. It's not easy to do, but it's not the impossible task I thought it once was. Oh, and helping others. Just by giving a friendly smile to a stranger or paying a sincere compliment to a co-worker makes me feel good.
So - this is my long-winded way of saying that yes, what you are experiencing is normal.