If I understand you right, you took the pictures when you were on the board of the company and gave the photo(s) to the president of the company. If that is the case, the argument the company would develop is that your performance is a work for hire. If you cannot prove the contrary, the company owns the copyright. What strengthens the argument to the favor of the company is that you gave the picture to your boss, the president of the company. Now that the president of the company is posting the photo on her personal website, this is the company problem. If the company allows it, you could do nothing about it.
You probably would be able to scuttle the company argument by proving that you took the picture at your time, privately, and you paid all the expenses associated with the production of the picture, and that you gave the picture to your boss for evaluation. Your argument would hold if that's true and, in the absence of written agreement to that effect, you could persuade other members of the board who were present at the time when you gave the photo to your boss to testify on the facts of the matter.
Many companies and institutions include a clause in the employment contract that the employee creation, even if it is done outside the regular working hours, is property of the company, the creator of the object would be entitled some royalty, and in some cases nothing. So, what was your contract with that company? If no such a clause is included in your employment contract, what implied obligations are stipulated in the statute of your State? I cannot be exhaustive on this forum.
You may disagree with my opinion. It will be wiser to consult with an attorney of your State who has had contact with this kind of problems.
Good luck.