Well, your pH is too low (acidic). For a soil grow, you want to shoot for a pH of 6.8 +/- 0.2. I would say that the visually depicted problems combined with the small size for a 2 month old plant are very likely the effect of your pH. If your soil pH really is 5.7 (as opposed to just the runoff), then your plant is not able to take in the nutrients it requires.

I would recommend flushing your soil with pH-adjusted water (of about 7.0-7.5) until your runoff reads around the 6.8 mark.