Oh Aries you poor bugger. Sorry I didn't see this last night.
I don't know if it helps but if you look back thru past threads you'll see you're not the first to have a crisis of confidence,I would say it's fairly normal...doesn't make it a nice way to be feeling though.
None of us can tell you if it's the right thing or the right time for you,and there are definitely always reasons why any given time may not be 'right'.
As far as worrying about your own abilities goes...I don't think that you have to be 'mumsy' to have a kid (fucking hope not anyway or I'll have to give mine back ) and virtually no one actually has the levels of patience that we all think a parent needs. And a newborn baby is,in my opinion,a fairly terrifying creature and really will turn your world upside down.
But all I can say is that if you want to do it,you will make it work. You may (like me) have lousy days where you feel shit at the whole thing and so tired you just want to cry,but in the end the small person that you make,and love,and find endless hilarity in,is worth all that shit.
Even in my darkest moments (and you all know I have them) I would never never change my decision. Because then I wouldn't have mani and he is just the most ace and amazing little person.
I have no idea if this helps AT ALL. But I really do feel for you. Now,join the bundle.