If you're going back and forth that radically, then you definitely shouldn't brush your doubts aside, especially when the idea giving you them wasn't yours to begin with.

As women, we've to a great extent been raised and socialised to be highly attuned to the needs of others, even to the extent that we confuse them with our own (witness the huge amount of guilt-based advertising that is aimed almost exclusively at women - mothers in particular; they wouldn't be using it if they didn't have some evidence that we were susceptible to it). Because of that tendency to empathise with and nurture the dreams and needs of others, it is all the more important that we be perfectly clear on what our own needs are. If part of you is saying "Hell no", then listen to it, understand why it's saying so, and try to figure out whether it's worry about feasibility or or simply a deep need to remain where you are at the moment.

Our impulse tends to be to sacrifice what we need in order to ensure that others get what they need. While being attuned to the needs and feelings of others is important, and one of the main ways we care for those close to us, self-sacrifice ultimately meets no one's needs. Self-denial leads to depletion of the energy one has to be there for anyone, and can lead to resentment of its beneficiaries.

So think it through, understand your doubts. It might be wonderful, but the key is to make sure that it's something you want, too, rather than a want of his that you empathise with.