What you are describing are typical signs that her period is arriving soon. It is also possible that the pill is causing it. It is unlikely to be a pregnancy sgn, as it is a bit early for that, and she is on the pill.
(The correct term is pre-ejaculate or pre-cum. You might have a misconception of what it is. If your penis glans was at all wet or slippery, It was from pre-cum. It gets secreted from your Cowper's glands when you get aroused, and has noting to do with ejaculation or cuming. If that does not happen, you will likely be too dry to comfortably penetrate her.)