Is this a normal behavior of a girlfriend ? Its URGENT!?

[Rajarshi]

My gf has some sort of a behavior problem with herself. She tells me that there is a fine line between she,her friends & me. I am ok with that. But what makes me feel sad is when I see her with her friends she always has something to talk about & she is so happy with them. She is happy with me too but sometimes we don't have anything to talk about. I wanna talk about those stuff which interests her the most. But she cant open up to me as according to her I've been her bf for the past 2 years whereas she knows her friends for almost 12-13 years, thats why she can talk about anything with them. Another problem is that, she says that treats me as her senior with respect as I am 1 year older than her but I don't want this age factor to come into play in our relationship. I even went as a volunteer to our school farewell party on my birthday. But when she heard the news she said that its a really stupid way to spend someone's birthday. BUT I just did it for her. I want to spend time with her on my birthday. That'll be the most special gift for me. I went to the farewell & we just talked for 5-6 mins & she said that her mom might come anytime & went away. I felt a bit sad though I was happy that I could be with her for a few mins. She has mock tests the next for days for preparation of her boards in February. We last chatted on Saturday, she told me how glad & happy she is with me but after that she says she can chat next 'maybe' on Wednesday night. What ? Is she a bookworm ? She is gonna study 4 whole days for MOCK tests ? She cant spare 10-15 mins to send an sms or call me or email or anything at all ? Now today only, she put a status on facebook saying 'Such a feelin's coming over me, There is wonder in most everything I see!', then when I liked it, she sms'd me & we had nice conversation for about 1 & a half hours in sms's. I'm really confused about my gfs behavior. Yesterday she didn't reply to my sms at all & said that she didn't have her mobile with her. Today I told her to come online & she came but just for 5-10 mins and she had to rush off for last minute preparations for her mock test in the evening. Whereas I saw the wall to wall posts between her & a friend for 1 whole hour, one hour ago. I always have time for her, but why doesn't she have time for me ? She says she is trying to balance time between her friends & me.....but is this the way to do it ? I don't think I am getting at all a treatment a bf should get. I am trying my best to do everything for her happiness but she ain't realizing anything. Am I seeking attention ? You guys tell me.....or am I being a bit too much smothering ?