Asking someone to change their medication because of the longterm health implications is not just broaching a subject. It is saying that you both have the same information and you believe they have come to the wrong decision - or, more likely, you believe you have better information on the topic and she should be guided by your wisdom. If you can’t tell the difference between that and “broaching a topic”, well, that’s not terribly unusual. If what you think you actually did was “tell all my girlfriends that I will be a completely reliable partner in behavioral contraception so that she would be safe from pregnancy without hormonal birth control, and then go away secure in the knowledge that she could make this decision based on her own evaluation of the risks and benefits of being on hormonal birth control, which are for many women far more extensive than preventing pregnancy”, well, that would be much higher communication skills and awareness on the topic than you’ve demonstrated here.

(Emphasis on the “because of their long term health” reasoning, because asking them to change because of exterior impacts can make sense)