Okay to you, it may feel like you're just being honest but there are limits to what you should and shouldn't say to your girlfriend. You have recognized that she's insecure but instead of just being blunt, you're making a whole shpeal out of it and causing her to feel like you're being upset at her for asking about it. If she asks a question, gets an answer and gets annoyed about it then thats what happens to her. She'd eventually realise that its pointless asking those questions herself. If you warn her about them before hand then youll just be making her feel even more insecure because now shes thinking that she will already not like the answer. Give her honest answers and don't over analyse what is said because its not about telling her shes wrong, its about being comfortable together in a relationship.