Jean, have you tried clearing your cookies or restarting your browser? It could be as simple as a glitch piece of code getting in the way.
I have almost 1600 followers on pinterest, and that grows by one or two a day. My tips are to pin genuinely, don't pin things you think your followers will like, it shows! Also find a niche, I'm really big in wedding(we're engaged currently), recycling/crafts and I hate about ten very specific etsy boards. It helps to be specific because you're more likely to bund by those with similar interests. Like instead of a general crafts board do paper crafts or clay or whatever you pin the most of. You become an 'expert'
Also, I don't let any of my boards go over 500 pins because then your board is two pages or more long (when you get to the bottom it says see more pins) and I just think that's too much and suddenly my board doesn't feel niche enough. But that could just be my personal preference.
I'm curious what you meant by pinning to your business account instead of personal? Do you have two pinterest accounts? If so you can only pin to the one you're logged into.
Edit - sorry about all the 'hates' I'm on my phone and it's convinced I always mean hate instead of have!