I have a lump near my adam's apple that i've recently seen and felt. i'm a young healthy and terrified woman (27). how likely is it cancer?

This may be a : Goiter. You should see a doctor for definitive diagnosis and treatment.

Few possibilities: It could be a swelling arising from thyroid, parathyroid gland, could be a swelling called thyroglossal cyst which is a remnant of a duct called thy.Glossal duct between tongue and thyroid , subhyoid bursitis (below a small bone callled hyoid ) could be a lymphnode, could be a pharyngeal pouch from a defect in muscles of larynx(old age), ectopic salivary gld .No need to panic. Consult your dr/surgeon.