I always imagined Betsy being Pansexual, due to the fact that she had a brief relationship with Cluster, who was a female version of Fantomex and the definition of pansexuality: "sexual, romantic, or emotional attraction towards people of all genders, or regardless of their sex or gender identity" seems more accurate to Betsy, taking the fact of Cluster and Fantomex into consideration.
Betsy being the one who "never quite get the hang of having a body anyway" just adds more in this "theory", at least for me...