Hi there, talking about bladder issues is par for the course, no question has ever been off limits in this MS community :D
I don't think what your talking about would be classified as incontinence, feeling or needing to frequently urinate is not the same as incontinence, an over active bladder, urge incontinence, urine retention etc.
If your only experiencing the feeling of needing to urinate without all the other issues that come with it, it sounds more like the typical sign of a urinary tract infection, which can cause the feeling like you have to urinate all the time, with or without burning or pain with urination. Feeling a constant pressure to urinate but nothing often comes out is a one of the top 5 signs of a UTI, the regular pattern you describe would be consistent with a reoccurring infection but a monthly pattern could also be hormonal related...
Have you had any basic UTI tests?
Hope that helps........JJ