I really, really, really recommend that you try to find a good dermatologist experienced with hispanic skin in your area.  You didn't tell what area you live in.   It makes me sad to think that these over the counter products are being sold with no warnings about the damage they can do, especially on the face.  I would never, never recommend liquid nitrogen on the face for melasma, especially in August.

 If you haven't read our section on melasma for all the basics about sunscreening (must block UVA!) and getting off contraceptives (with doctor's approval) that could be aggravating the melasma, please go read it first.  I think you would benefit from a prescription bleaching cream (your dermatologist has lots of options and can help you find one that works for you) coupled with a series of light peels.  The peels are usually done about 4-6 weeks apart in a series of 3-6.  Dr. I