I have a 6 week old baby and she sleeps for only 45 minutes per nap each time. Sometimes she will go an hour but usually never more then that. I read she should easily do an hour and a half but that is almost impossible it seems. Is 45 minutes okay? Any suggestions on how to make her sleep longer? I tried picking her up and calming her down once she wakes to try to get her to go back to sleep but she never does even though she is still tired and will easily go back to sleep if I hold her. If I put her back down in her crib she wakes up again. Its so frustrating!
I should also mention I do swaddle her. That has majorly helped with getting her to fall asleep and she does sleep longer at night. Usually a 3 and 4 hour stretch at night. Its just during the day that she doesn't sleep very long.

Re: My baby wont nap longer than 45 minutes?
Have you seen the post I often paste? I would recommend putting her down awake after 50 minutes or so.
Disclaimer: Do what works for you, this is what we do.
We keep an eye on the clock and keep DD2 up for only a certain amount of awake time (which at this age is basically enough time to diaper and feed her and play for like 5 minutes - 60 minutes of awake time for her). See below for guideline by age. We put her down awake, to fall asleep on her own. No crying necessary. By not letting her get overtired, she is able to fall asleep on her own. Also, by putting DD2 down in her space awake, she does not wake up in a different place than she fell asleep (i.e. she doesnt fall asleep in my arms, then wake in her crib and be scared).
We also swaddle using the escape proof swaddle. I personally swaddle till about 5-6 months old. We thought DD1 hated swaddling, so we stopped at 2 weeks old. Then we found this method at 10 weeks and she fell asleep for 7 hrs that night. It works great for us: https://www.youtube.com/watch?v=5K4VdZxwsu4
We also have a fan for white noise and a fisher price aquarium for music/lights to distract her. And, if necessary, a pacifier. I highly recommend a crib attachment thing, like the aquarium, not a mobile. A mobile needs to be constantly wound up whereas the aquarium plays for 18 minutes and has a wireless remote that can turn it on from the doorway.
Guideline for Awake time for babies
0-4 weeks: 30-45 minutes
4-6 weeks: 40-60 minutes
6-8 weeks: 40-70 minutes
8-12 weeks: 50-80 minutes
3-4 months: 60-90 minutes
4-5 months: 1 hr to 1.5 hrs
5-6 months: 1.5 hours
6-9 months: 2 hours, give or take 15 minutes
My DD is also 6 weeks and does the exact same thing..after eating, being changed and tummty time it usually has been about an hour and then I spend another 20 mins or so getting her to sleep only for her to sleep mayb 30-40 min to wake back up and do it all over again. She fights sleep soo bad. I figured this was her way of knowing her days/nights as she does sleep in 4-6 hour stretches at night now for the past week. But it can seem frustrating cause as soon as I get her to sleep..i feel like she is waking up again and I have barely had time to do anything..My DD also wakes ups again as soon as I put her down after she falls asleep unless I make sure she is completely out before putting her down.