Learn from this whole experience, and move on? Like you, I started w/ PET bottles because I needed something to put my first batch in. After that, I started collecting glass bottles, and moved to those pretty quickly. I don't like the PET bottles, because they don't seem to hold pressure very well. I think it's because they're somewhat gas permeable. Which also has implications for the beer going stale.
So... Hopefully you learned a lot from your first attempt, and don't get too discouraged. I'm about 4 years into this hobby now, and I'm still making significant adjustments on almost every batch.