First up, you're not doing anything wrong.
Some babies don't do routines, so forget about it if that's not working. If you're worked up, very tired (or have a headache) then getting your mum or someone else in to give you a break is a great idea. Sounds like you need a little R&R. We all know those first couple of months can be incredibly hard - even harder when baby doesn't conform to our ideas of how things should be (ie, sleeping at least a little bit!).
I'd say also you're probably extra tired because you've got an older child as well, no doubt that makes things harder still.

Cut yourself some slack, ok, you're not a horrible mum at all