Let me start by saying that I'm not familiar with the PFS rules, so if this isn't applicable/allowed, sorry.
Another option could be to take the Master Chymist prestige class, which gives you effectively two or more mutagens to use in case of emergency. The main drawback to this is that: A) you can't take anymore discoveries until you take more levels in alchemist (which I don't think should be a problem if you're focusing on mutagens) and B) you have a chance to be forced into your mutagenic form when you might not want it. It also adds more roleplaying since your mutagenic form now gains its own identity and alignment.
If you want to take a closer look, here's the link: http://www.d20pfsrd.com/classes/prestige-classes/other-paizo/i-m/master-chy mist#TOC-Advanced-Mutagen-Su-