First- Congratulations on nursing your little one, even though she is a long nurser. Hang in there..she needs you :-) Everything only last for so long and then each phase passes. All of this time only lasts for a blink of an eye, then it's gone...do whatever you need to in order to make this more enjoyable...
I second the recommendation of going to a babywearing meeting and finding out about a good sling and wearing your baby so you can get up/out and do other things rather than sit home staring at a newborn all day! You can wear her or nurse while cleaning, cooking, using the computer, reading, walking through the neighborhood or the mall! There is really no need to stay home all day and doing nothing else!
It is totally normal for a baby to want to be held alot, especially when napping. If you giver her what she needs now, you will have nurtured a baby into becoming a well adjusted child that is secure and trusting and relaxed/comfortable rather than insecure and anxious. Keep her close. I remember my 1st being a major adjustment for me too...your entire world has just changed and it is no longer easy to do everything you have enjoyed for yourself (reading, crosswords, vacations, hot baths)....now you have a baby to focus on instead and this is a huge adjustment for a 1st time mom to now switch focus from yourself to someone else. Don't worry, you are normal. Once you become adjusted and let some of that go, you will be happier with providing for her needs and giving up some of the things you used to be able to do all the time.
Join a local moms group or baby/mom activity center! Come out to the Morton Plant Nursing moms care/share group held at Morton Plant Hosp every 1st and 3rd Fri of each month...you can get support (like this, but in person) from other moms and the lactation consultant for everything from nursing to parenting, including depression. There is also the MOMS Club where you can meet other new moms and attend regularly scheduled playdates/meet-ups to get out and see other people. You can attend mom/child activities at Gymboree, local hospitals, local gymnastics centers, parks...many places! If I hadn't gotten out and gotten involved, I would have probably started to get cabin and baby crazy too :-)
I would get a Dr opinion on pp depression (it's common and treatable!) - you really want to feel differently about your newborn and your parenting experience, this is a time to cherish and remember.... I would get out and get involved, talk to other moms and get some advice and help for how to make things more enjoyable and easier (like babywearing). I wish you and your newborn the best!!