It's a bit embarrassing to admit, but after producing for 2 years I've only finished a few songs.
A "few songs" just isn't enough... come back when you've done like 100. Watch this
https://www.youtube.com/watch?v=PbC4gqZGPSY and this
https://www.youtube.com/watch?v=hqZAxLqJkzA&index=59&list=WLI have a hard time getting all the frequencies to be as balanced as I hear in professional tracks.
So work on it! You already know what you need to work on. Mix with reference tracks, put them up against your track, I mean literally place them in your DAW and A/B them against your track. Listen to professional mixes attentively. Analyze them with spectrum analyzers... etc..
I would rather produce 1 masterpiece than 10 turds but I feel like because of that it takes me a long time to finish my songs.
This is the wrong way to look at this, it does not work this way. Watch the first video I linked again. You're not going to write 1 masterpiece if you've only written 10 turds... you need to write more like 100 or 1000 turds, seriously.
At the same time however I feel like once I'm finally able to habitually get good mixdowns the songwriting speed will eventually catch up to me.
Again, focus on your mixdowns for a few weeks/months. Grab some unmixed song files here
http://www.cambridge-mt.com/ms-mtk-newbies.htm#Triviul and get to work. Practice mixing A LOT to the point that you feel you've gotten somewhere.
Should I be concerned about my producing speed?
No. Your concern should be more about how you can get your 10,000 hours in, since it takes about 10,000 hours of practice to be a master at any given skill.
Will my producing speed eventually get faster as I get better?
Or course it will... if you practice something over and over again, you get faster at it, right? Also, there are things like setting up your own templates so that you can make the process even faster.
What are some things you do that helped you get past the same situation that I'm in?
Un-plugging the Internet and getting to work. Doing something about it. Putting in the 10,000 hours. I know there's nothing glamorous about it but that's the truth.
You have identified the problem yourself ... the problem is not about writing faster... the problem is that you feel your mix downs are sub-par. What you need to do next is already cut out for you.