Hello!
Just wanted to say hang in there! It DOES get easier with time & from birth to 6/8 months their sleep needs are constantly changing, different needs all the time and its just so tough. I think if you have an angel baby, great, they sleep! And well! But a spirited/grumpy/touchy, oh boy its hard.
I think for me i just had to let go of that routine for a while, sit back and watch the babies cues. Go with the flow. Its a hard step to take but for your sanity, its a better step to take. Just for a while, while you ride it out. I also had an almost 3yo at the time too, luckily he is the angel baby described above lol.
Honestly from 6/7/8 months, after transitioning to 2 naps, it totally settles, you will find.
I remember when DD was about 3m/o and she had had about 4 30 min naps all day by the time DH got home at 4.30pm she was grumpy & screamy, i was in tears wondering how the heck im going to fo on like this! DH took her from me in that instant took her to another room & eventually got her off to sleep. Just that one part of the day, with that little help, is what i needed. Do you have anyone that is able to step in like this in a time of need?
One thing that hasnt been mentioned is wake to sleep, wondering if you have tried it? Go in at around the 20 minute mark & stroke face/rub tummy, anything to get her to stir a little. It helps break the sleep cycle & *can* help lengthen the nap.
Other than that though, i drfinatley just think you should take a step back, stop fighting for something that just isnt happening, and go with what baby wants. You will probably still get the same n/w as what you are now anyway, but being a bit less structured and and bit more 'screw it' is probably going to help you here
It does get easier!! KEEP GOING you can do this xx