Daughter is bored - why?

My 7 mo old daughter is always so bored when I'm with her, and cranky. She goes from one activity to the next without much interest or enthusiasm, smiles and giggles not too often, and just generally seems frustrated. I'm a stay-at-home mom and I'm with her full-time. I've tried everything! I try to play WITH her, for example in books they recommend games like pop goes the wheazel, peekaboo, patty-cake, holding babies hands and making her clap or making her touch your face, etc. and she hates when I hold her hands and pulls them away. She is generally uninterested in any games like that, and if she is, she's only interested for maybe two times, then, even weeks later, she's still bored if I try to play them again. I give her toys, and the freedom to play with them both WITH me and to explore on her own. I rotate them, yet she still seems bored with all of them, no matter is she's playing interactively with me or by herself, whether I suggest ideas for games or whether I follow her lead. She only likes 1 book of all the the books I try to read but only stands it to be read maybe three times in a row then it's over for the day. I try tickling, talking, showing her things, letting her show me things, playing with toys, letting her play along, letting her discover water or cups or objects, different rooms, changes of scenery, location, voice. I show enthusiasm and praise. I make up games, I let her make up games. Nothing works. She rarely smiles at anything I do. She gets so bored and agitated with her toys no matter how I rotate them. I do give her regular (and needed) naps, so it's not just being tired. She comes from a loving home without drama, and two attentive parents. She doesn't seem to have attention deficit and I would doubt that she has autism because she does fine playing and interacting with almost anyone else. I mean there's no doubt that when she's tired or hurt or scared or sad she wants me, but all other times she's just flat around me. The only game she likes is if I carry her around all day and show her objects but she's a HUGE baby (not fat just big) and I can't carry her for long before my arms ache and she won't let me use a sling or a carrier with me. What is going on?? I'm an attentive, serious, loving mother who has only ever wanted to do what's best and right for my daughter. I thought my intentions and love would be enough to make her happy with me but obviously my efforts are failing for some reason. I have no clue why. I read books, I try to implement everything I can, it was a planned pregnancy, I've wanted to be a mom my whole life. I can't imagine what's gone wrong, it's certainly not for lack of trying. Lots of effort, lots of hugs and cuddles, songs and experiences. I feel awful! I have two questions. The first one is, has anyone had a simillar problem? is this common, and what might be the cause? and the other question is: does or has anyone had a child like this and what were the methods you used to make them interested and engaged? any game suggestions?