Is irregular menstrual bleeding on Spironlactone a problem?

Hi, I have taken 100mg spironalactone for 16 months for adult acne, and 5 months ago increased to 200mg as I was also diagnosed with androgenetic alopecia. I am a little worried as my periods have now become slightly irregular (1-2 bouts of bleeding between periods). Is this ok? I'm worried I'll have to reduce my dose - spironalactone is my only option (I spent 15 years on Dianette and Yasmin until they caused melasma on my forehead). Could you advise me at all please? Many thanks.