Yes, this could be the pill. Please give it three full months to adjust!

I agree with Eiri. You need to give your body the full 3 months to fully adjust to the added hormones. For some women, it can take a little longer and others a little less. Every body is different.

Although it's probably unlikely that you've actually gained weight yet, you could be bloated from the pill, and the moodiness is definitely possible. But do give it some more time and stick it out.