I've been working at my job for almost 2 years and I am a full time employee. In the past couple months i've been getting anywhere from 12- 30 hours. When I talked to my boss about it she told me to use my PTO. Well I don't have very much

I've been working at my job for almost 2 years and I am a full time employee. In the past couple months i've been getting anywhere from 12- 30 hours. When I talked to my boss about it she told me to use my PTO. Well I don't have very much PTO and I don't have a set schedule so I shouldn't have to use my PTO just because they won't give me my hours. Is there anything that I can do about the situation?