Congratulations! As a clyde who started commuting ~9mi RT 4 days/week about 6 weeks ago, I can tell you it's totally worth it. My strength and stamina are way up, I've made some new friends w/ other bike commuters at my work, and it's inspiring to my daughter. It did take me a while to figure out what I liked to wear, so I'll share what I came up with. I live in a dry climate and morning commute temps have been ~25-45, so YMMV based on your circumstances.

1. You are already doing this, but the bike shorts under the work pants has been great for me.
2. Polaterc makes a fabric called Power Dry which is fantastic (various manufacturers use it, I got some long-sleeve shirts from REI). It is a 2-sided fabric and the inner layer wicks really well. It keeps my skin dry during the ride and, by absorbing all the sweat, makes me stink a lot less before I clean up.
3. Get a lightweight jacket with pit zips! Traditional layering is hard on a bike since you have to stop to add/remove layers. With pit zips you can adjust them along with the cuffs and main zipper to help regulate temperature without stopping. I also often start with some behind-the-head ear muffs that I remove part way through the ride.

and my favorite tip: Don't ride a fast bike. That way it's obviously the bike which is being slow