Wow man, well done! I think my mediums looked about as worn as your softs, very impressive. I must be terrible at tire-saving, lol.
I lost a couple races to a real fast guy who was using softs without stopping and his rear tires were literally 100% red by the end. I started using softs up front and mediums on the rear after I saw that, and I could still barely manage the last lap. I was pulling low 3:04's on my best laps. If I remember correctly, the lap times on my better races were something like 3:08, 3:04, 3:07, 3:09, 3:12, bringing total time to ~15:41 for the better few of my wins. One race I pulled a 15:39 and I think that was my best.
edit: pit lane starts on the short straight after the the Corvette Curves, right before the first Ford Chicane. Instead of turning slight left into the Ford Chicane, you veer to the right and enter the pits. There's a chicane on pit lane right before entering the pits too, so be careful when you actually do use it.