First, congrats on the new baby, and try not to stress out too much. While no one can tell you with absolute certainty how things will turn out, I think that if you have not seen very rapid growth by 2-3 months of age, it is unlikely that the hemangioma will suddenly get exponentially larger.
I do think that you see the worst cases on the internet. You likely have known plenty of people that had hemangiomas, or their kid has a hemangioma, but it was small and you didn't take note of it. It is always good to get a second opinion, but don't spend time obsessing about it - try to enjoy the kiddo while she is still a baby.