I feel like Gabe gets overstimulated too fast. I know it is because he only naps for 30ish mins at a time now. So, it's not really enough to be non-pissy.
During the day goes about 1hr between waking up and getting angry again. Right after he wakes up in the morning he is happier because he slept. But, not today. He didn't sleep well last night, so he is extra grumpy.
I don't have a lot of experience with this age. Plus, I constantly worry that he will have long-term effects of his prematurity. Blah!
Re: How many hours a day is your LO fussy/crying @ 3/4 months?
I think if I add it all up over the day, maybe about 2 hrs. And that is mostly in the evening
But E is definitely become a worse and worse napper so I think that time will be increasing. Sorry I'm no help, but you already know that 
I think I'm going to attempt more "play" and see if that wears her out enough to nap and thereby avoid evening meltdown. I'm open to suggestions! LOL
Yes I would agree with pp approx 2 hrs and mainly in the evening. Plus a couple of other times during the day when LO is tired and ready for nap.
I constantly change up our 'activity' so feed, play, jungle gym mat, tv on, jumperoo, hold and sing, nap, high chair for food etc.. we are always doing something. For the most part she naps very well now but never used to. Obviously I can't sit with her every second but I try to give her quality time as most moms do. We all still have our home responsibilities laundry, make dinner etc.. I try to involve her let her watch me and sing at the same time. It helps 'redirect' her mind constantly. If she is super fussy and I can't get anything done I go in the bath with her or the shower.
1 hour is about how long LO could go before he got pissy, up until around 4.5 months. Now he usually goes about 2 hours before getting super cranky again. He only naps for about 45mins- 1hr 3 times a day (if we're lucky).
I think that awake time is pretty normal for his age.
About an hour, but all kids are different, I know DS # 1 fussed much more than DS # 2 does at this age. The sleep issues at 3/4 months are attributed to a growth spurt. DS # 2 is waking every 1.5 hours at night, and I have friends that have LOs up every hour.
DS # 2 naps anywhere from .5 hours to 2.5 hours.
I'd say hourish. She really only cries when she's hungry, bored or tired. So if I give her what she needs ASAP, she's good.
She's pretty non-fussy usually.
I will say today though she's a CRANK. She's napping now but we'll see how long that lasts. Last night she was up every hour for some stupid reason and today as soon as she falls asleep she scares herself awake and shrieks.
H and I just salined her nose at lunch though...and it made her happier again. I think she hates laying down. She's not sick..just dry air stuffy. She's in her carseat napping now and seems fine.
I will say and not that this is help to you but my preemie twin neice/nephew were fuss budgets at this age too. Easily over stimulated, hard time going down, general fussiness. It's like they knew what they had to do but didn't have the coping techniques developed to make it happen.
Same here--at this point one hour of awake time is as long as she can go before getting fussy--at that point we start winding down for another nap.