I know it is safe to have a pack of condoms and use it whenever you are ready for sex, but that doesn’t mean you have to rely on those plastic bag if you make sure your partner is free from STI and she is already in pills to counter pregnancies. However, my challenge is to initiate a positive and neutral conversation to discuss about STI in relation, so your partner feel comfortable to discuss the problem without lying you and eventually making you the victim of STI. How to initiate this kind of conversation?
It seems like you are very proactive in sexual health and that is a very positive thing. As long as your approach to discussing it comes from the same perspective than I think you are good. If you cannot trust your partner or think she is lying than follow your intuition and maybe she is not the right one to be have relationships with. However, if you say something along the lines of, ' I really enjoy where this relationship is going, I'd like to take it to the next level, perhaps now is a good time to talk about sexual health and history, so if there is anything we need to take precautions for we are doing that'. Maybe non-verbally saying you accept her either way and you just want to make sure you are practicing safe sex for both of you. The key is to have trust in the relationship! To briefly discuss the last part of your post, 'what if she lies to you and you contract something later' while that would be devastating, it is not the end of the world. There are millions of Americans who live with STI/STD's and they have normal happy and healthy relationships so if you ever find yourself in that situation you just have to keep your head up and move forward.
It is great that you are so into having safe and healthy sex-that is so important! However, it sounds like if you have to think that your partner is lying to you, it may not be the most healthy and safe relationship. STDs and STIs are serious and should not be taken lightly or lied about. When talking to your partner about such things, it should feel comfortable and safe because you want to protect one another from passing anything along through having sex. Initiating this type of conversation may be hard to do and awkward at first, but if you remember the importance of the topic, it may become easier. Maybe start the conversation with something like, "Because I cherish this relationship and I love you, can we please talk about...?" This will help your partner to know that you are asking and initiating the conversation out of a care and love for yourselves and the relationship you have. If you feel as though she will lie to you about it though, maybe she is not the one for you because that is not a sign of a healthy relationship. If one of you were to have or receive an STI or STD, it really is not the end of the world, just a consequence that you have to live with probably for the rest of your life. So keep your head up and look at this potential conversation as a positive thing and put trust in your partner-it's important!
I think that if you have the commited relationships it should be discussed without hesitation. It does not mean that you do not trust a partner but it is about your health. A normal partner should understand this in the right way.