My DD was like that. I wore her in a sling for a lot of naps or held her. Eventually she became more amenable to being put down, but I had to do it at just the right time in her sleep cycle. If I waited too long, she'd wake up, too soon and she wasn't asleep enough yet. It took a lot of experimenting but we eventually got there. She was also one to wake at 45 mins and need help getting back down often. But really it doesn't last forever and she was my only child so what else did I have to do than enjoy cuddle time with my baby? I did make sure to have noise around at nap time, tv on or music or something so we wouldn't have to worry about other sounds happening and waking her up.
She really is too young to be left to cry. I wouldn't CIO an older child either but even Ferber does not recommend his CIO techniques until at least 6 months. Uncomforted crying is not good for babies. The stress hormones are no good for developing brains. I believe you can find scientific studies on this on askdrsears.com, if you need science to confirm what your mommy instinct is already telling you. She is still very young.
I'd also recommend Happiest Baby on the Block. Another good one for gently helping babies to sleep on their own is No Cry Sleep Solution. Mostly geared toward night sleeping, but could be helpful for naps too. It may take a lot of experimenting to see what works for your baby or if she's like mine, it didn't matter what I did, she did things when she was good and ready and not a moment before. She's almost 2 now and naps stopped being a big deal ages ago. I really don't remember at what age.
I know it can be frustrating, but do some more reading on gentle techniques rather than listening to people who tell you to do something that doesn't work for you. There's a reason it makes you feel bad to hear her cry. It really isn't a choice of either CIO or have the baby strapped to you forever. I know this seems so far off to you now. But I wish I could spend a couple hours with a baby sleeping on me now while I watched a movie. Naptime now is me squeezing in lots of chores, eating and me-stuff. Good luck!