Does Bella nap in the day hun? If not it could well be overtiredness with a bit of colic. We really struggle to get Seth to nap, he won't go down for his big sleep until 11 ish. By 8ish he's tired and stroppy and gets so cross that only way I can calm him is to hold him constantly and bf until he eventually nods off at 10.30/11.00. It's so tough when they're grumpy
The only way I can get him to nap is in his pram and it makes such a difference to our evenings when he's napped in the day.
I do think some of it is just wanting mum though, it's easy for us to forget that they're still only tiny and we are the world to them. And it does get easier, I was either holding or feeding Seth pretty much constantly for the first few weeks but now he's a lot happier to play on his mat by himself and entertain himself for a bit. He seems a lot happier over the last few weeks and we're getting lots more smiles too! Hang in there xxx