If you just stopped Effexor and you were taking some whole-pill sized dose and you didn't go to another SNRI or to an SSRI, then you are almost certainly in withdrawal.

I don't know what dose of Effexor you were taking before you started tapering or what the last dose was before you stopped.

But yes, if you just stopped the Effexor, it sounds more likely that it's withdrawal.

This is a change of topic, but do you know what antidepressants are safe to take during pregnancy? I think Prozac and Zoloft are? I don't know about others like Wellbutrin or older ones, like the tricyclics.