Not to be flippant, but when it's right, you just know.

If you have doubts, it's better to break the engagement, or at least postpone the wedding indefinitely, than to find yourself in (what could turn out to be) a bad marriage. BTDT. If you feel your symptoms are due to the stress of the situation, I would absolutely say proceeding now is a bad idea. Give yourself more time to find out what you really want.

All the best,

Cheri