I'm confused really... Does he care or he is just using me for ?

I spent the whole weekend with my Boyfriend and everything was good. I actually felt like we are growing together as a couple. The next Monday was my birthday I didnt say anything to him cos i remembered his without him reminding me. COme my birthday the day after everyone remembered and send me nice birthday wishes. I was hurt but i held my Composure. Late that night he sent me an sms as usually checking up on me. Even when i'm sick or low i know i can always count on him. He is always there on my side... I asked him how come he always sents everyone Birthday wishes except me. He said he had not realised it was my Birthday.. He is on Myspace and FB you get those reminders.. Does it mean maybe i'm just there for and he doesnt care about me at all. But is not all we do as well.. i'm so confused and hurt! I know he is going through a rough patch with work at the moment, i dont know if i'm looking for excuses for him cos i love him. Or is it he just doesnt care about me as much as i do. The otha thing is when i confronted him he was a bit Rude to me about it as well he sort of snapped at me. Thats not how i know him. I dont know what to do, are these the Red flags they talk about. Everything was perfect expect my birthday!