Swimming Update

Lately, I've been swimming about 5 days per week and am up to 30 minutes of continuous swimming - not all freestyle. While my swimming condition is improving, I use a combination strokes to swim continuously for 30 minutes; also, I don't do flip turns. Generally, I start the first two laps freestyle, followed by a rotation of breast stroke - back stroke - freestyle. I don't count laps but know that my freestyle speed is about 30 seconds/lap (25 yards); my breast and back stroke are much slower so I'm guessing I swim a bit under 1/2 mile in 30 minutes. My technique is improving but I still struggle with breathing on the freestyle; I don't always get a clean, full breadth when I turn my head. Also, I typically swim after an hour of working out with weights and possibly a jog or incline walk so maybe my stroke might improve if I swam first:)