You don't sound like a crybaby at all. When dd was 15 weeks old, I was finding it very hard to cope, and could hate dh just for being able to read a book when all I was doing was feeding. I found it hard to get out of the house, meet anyone I liked, or do anything much.
As everyone else says, it is hard, it will get better.
But - and please don't be offended by this - it does sound as if you are just a bit depressed, and see going back home as a way of 'making it all alright', when you'd probably miss dp horribly and still be stressed. Do you have an understanding doctor or even HV you could talk to about this? The stress and the hormones play havoc with your system and your moods, and I think probably most women have some form of depression at some point, and quite often it hits at the four month mark, when the elation wears off a bit.
I had horrible PND at just this point, and was crying all the time, as well as shouting at DH and found several other mothers on here in the same state - all at about the four month mark too! But just talking about it, and admitting that everything wasn't perfect, made a real difference to me.
Sorry this is a bit long, but hang in there.