You very likely did give the company permission by allowing the photographs to be taken for the purpose they're being used, for allowing them to be published, for not immediately objecting when they were published, and for not taking any action to stop their continued publication.
Although everyone has a "right of publicity" that prohibits others from using their name, image, and likeness for commercial purposes w/o permission, you sat on those rights and only objected after your girlfriend left the company. Sounds a case of sour grapes.
The analysis -- which is heavily fact dependent -- is whether you granted the company an "implied license" to use your image for their advertising. There are always facts in play that are important that are not [and should not be] disclosed in a public forum such as this one.
There is no getting around the fact that if you want the company to stop using the photographs you need to discuss the matter with your own intellectual property attorney.
Using your image without your consent to advertise their product violates your state "publicity" rights. You don't state how much time has transpired since the company used your image, and as my colleagure points out, the passage of time could create an implied license, and a "laches" argument that you've sat on any rights you may have had and your assertionn of them now would prejudice the company, whcih has spent money on these advertisements.
The company's use of her photographs of you without her consent would infringe her copyright, but if she was working for the company doing this and she took your photograph in the course and scope of her job, then her employer owns the photos, and they may have instructed her to obtain your written consent to use your image. The fact that she was a doctor makes it questionable whether this was part of her job, and you identify the research as "personal," but if your girlfriend did this while performing testing of some drug, acquiring test subjects and documenting the results may in fact have been part of her job as was NOT personal research.
Both you and your girlfriend need to see an AZ lawyer to fully disclose the facts of your situation.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.
I agree with my colleagues but I would add the following. Even if this was not a case of sour grapes, and even if you are not barred by the doctrine of laches, your right of publicity claim probably has little economic value. Further, in order to obtain an injunction, you would need to establish that continued use of your photographs causes you irreparable harm. Since you volunatarily appeared in the photographs and did not originally object to their use, it would be hard for you to prove that you have suffered any harm from continued use of the photographs, much less irreparable harm.
Nonetheless, your question is incomplete in many ways, and there may be other facts and circumstances which would give rise to a viable argument that the company should not be using your photograph. I cannot give you definitive advice on this question without knowing a great deal more about the facts and circumstances, including (a) the relationship between your girlfriend and the company, whether the testing work was part of her professional work for the company and whether your girlfriend would testify that you consented to participating in the photographs, (b) the time between the date when the photographs were taken and the date that you first objected to their use, and the circumstances of such use, (c) the nature of the company's responses to your objections to use of the photographs, (d) the cost of changing the company's advertising compaign to eliminate use of the photographs, (e) your professional and personal background, and whether use of the photographs could cause you economic or other harm, and (f) many other facts and circumstances that could be relevant to these issues.
This is a great example as to why individuals should not rely or make decisions based on legal advice that they received on-line. The general guidance that lawyers (such as myself) provide on web-sites can be useful, but it is no substitute for a full and complete consultation with competent counsel. I can imagine many extraneous facts and circumstances that might give you a good claim against the company arising from its continued use of these photographs, but the details that you provide in your question are insufficient for me (or any other lawyer) to make a definitive judgment on your case. Thus, you should retain counsel to help guide you through these issues.