Is there a limit on the number of builds you can have?

You probably mean “jobs”. See Newcomer question: what are builds, jobs and stages? - #2 by native-api

Your build only defines 10 jobs ( php 5.4, 5.5.9, 5.5 etc) so it’s all as expected.

You can use https://config.travis-ci.com/explore to verify what your .travis.yml is parsed into.