Am I a bad boyfriend? Sometimes I feel I'm not making her happy or I'm doing something wrong.

A relationship is not an one-man game. It takes two to play it well. You think that you are a bad boyfriend. Have you ever asked your girlfriend about how are you? Asking something like, "Do you feel happy when staying with me?", "Did I do something that hurt you/ making you feel sad?" or just simply "Am I a good boyfriend for you?". It may be hard for you to ask something like this, but communication is the key. Be proud of yourself, ask her, and improve.

Talk to her! You and her are the only ones who know exactly what's going on in your relationship. If you love each other, or even just like each other enough to date, you owe it to each other to communicate. As silly as it may sound, literally say things like "What do I do that you like?" "What do I do that you want me to do differently, if at all?" "How can I make you feel happy/loved/appreciated/heard?" And then answer those questions back when she asks you the same thing! Sometimes the best way out is through and the only way you'll know what to change is if you know what needs to change.

All we can do for the people we care about is communicate that. If you’re worried you’re doing something wrong, the best thing to do is talk with your partner and share your concerns and your intentions. As long as you have that open communication and listen genuinely to your partner, you’re doing your best. It’s hard not to doubt yourself sometimes but remember that you are both choosing this relationship and as long as you’re showing you care through communication, you’re doing your best. You should also reflect on why you are feeling this way, what aspects of your relationship are making you feel as if you’re not enough.