Jessi Spencer-Hammac and her dog, Rocco, spend time on their porch in Tampa, Fla. Spencer-Hammac has bipolar disorder and now pays for her treatment out-of-pocket. But under the Affordable Care Act, insurers are barred from turning away those with pre-existing conditions. For Spencer-Hammac, it could mean a big savings on her medication and give her the chance to see her therapist more often.

MIAMI — Before she was diagnosed with bipolar disorder, 32-year-old Jessi Spencer-Hammac thought she was just a moody, restless dreamer who had trouble finishing projects.

At times, she alternated between being hyper-social and abruptly ending relationships. She also made rash decisions, such as moving across the country and losing contact for a couple years with her young daughter, who was living with the girl’s father at the time.

Up one day, she could swing quickly to sad and withdrawn.

Spencer-Hammac said she did not seek mental health treatment until a few years ago. Because she cannot afford health insurance, she pays for the counseling and prescriptions out-of-pocket. But under the Affordable Care Act, insurers will be prohibited from turning away Spencer-Hammac and millions of other Americans with pre-existing medical conditions, as they can now. Insurers that do offer coverage to those with existing conditions typically charge such high premiums that it is unaffordable.

For Spencer-Hammac, the provision in the health care law could mean an end to buying her $100-a-month mood-stabilizing medication at a discounted price in Canada, as well as the chance to see her therapist more regularly.

Her husband Chris, a 40-year-old bartender who makes about $35,000 a year, has health insurance through the Veterans Administration, but his policy does not cover family. He was recently diagnosed with testicular cancer and underwent surgery in August, further stressing the family’s finances. Their 12-year-old daughter, Marley, has coverage through her step-mother’s job.

The National Institute of Mental Health estimates that 6 percent of Americans live with a serious mental illness. One in four adults, or about 57.7 million Americans, experience a mental health disorder in a given year. Many don’t have access to treatment or lack insurance plans that cover mental illness.

The Tampa mom tried to get health insurance about eight months ago and was told by one consultant that she would never get coverage for mental illness as an individual. She searched for plans online but was inundated with phone calls from insurance companies she said were so manipulative that she gave up.

“I felt marginalized, like I didn’t matter, and mad ... that my struggle and the things that I deal with don’t matter,” she said.

Spencer-Hammac, who is about to start working again as a waitress, pays $40 for a family physician to write the prescription for her mood stabilizer. She can’t use the generic brand, so she buys it in Canada and orders several months’ worth to avoid high shipping costs. Sometimes, she worries the order will not arrive on time, so she regulates her dosage.

“If I stop it abruptly, I’m looking at being very unstable. That’s always been a stressor,” she said.