I know what you mean by apparent increase in "bad behaviour" -- but I will return to this in the second half of the post, first let me ask if a recovering shouty mum can join the lair?
I became a shouty mum as soon as I returned to work. TOo much stress at work, plus housework, DH not really comprehending even half of it - plus a typical child-like behaviour, nothing really bad, just normal -- mix these ingredients well, and the result is a shouty, lopsided cake of parenting.
Thankfully, just like you ladies, I kept searching for better ways. One book I found (books are useful as they offer a more systematic approach, for the rest of it, there is mumsnet...) was "When your kids push your buttons". Might be helpful to some, it was to me but without comprehending what was behind some behaviour I hated the most (tantrums, whining), it was just half the solution. THen I even read a book on anger management, that was actually a very good book, I think it was called "Taking charge of anger" - it had very good and practical approach and many tips. But I still could not stop getting angry and shouty when my buttons seemed to have been pushed. Then DS2 came along. As a result, work stress lessened and i had a chance to remember what kind of a mother I am when not stressed. That has helped with my own feelings of self-worth.
Yet, when really stressed, I still shouted, even though I could see it was useless and how DS1 started talking back (rightly so). The trigger was usually crying and whiney demands which did not seem to end. When DS1 tantrumed I would always be quick to stamp it out. So instead, he seemed to hold onto his very strong feelings and just seemed generally miserable fairly often. Developed strange fears. Maybe it was the age but I think it was also knowing that mummy can sometimes become a real monster - and that mummy does not really understand him, or his feelings (let alone her own). Then I ran across a book on "Tears and tantrums" - and that has really changed things for me.
First of all, it helped me realise that I am not responsible for stopping the tantrum or the tears and for mending that particular broken cookie. Instead, I realised how necessary it is for children to cry and to have tantrums and how I can welcome these as signs of a healthy ability to communicate feelings rather than something manipulative. When we accept that children are unable to tell us about their stress and upset and instead tantrum (just like we shout instead of finding better ways of helping ourselves), it is easier to accept such feelings. Instead of stamping them out, we can help by staying close or even holding in a firm but loving embrace the little tantrumer. THen they often start to cry, which is very useful to get out the stress and upset (nothing better than a good cry, hey?). When we show them we understand that they are upset and angry, it also frees us from having to give in to their demands. I am sorry, dear, you cannot play with the scissors, I will put them away. Then we can accept that they are angry -- who wouldn't be when not allowed to do something that they wanted? In the case of children we for some reason want to stop that expression of anger by tantruming or we walk away from it. This does not diminish anger or tantrum, well, it will stop at some point but the feelings are still there. Anger and tantruming come from feelings of disappointment or even fear. If expressing feelings (at that age, by tantruming as well as crying and whining) is accepted, those underlying feelings will come out, rather than get bottled up, producing another future shouty parent.
Over time, children learn their feelings are all right to be expressed and learn to express them with greatest efficiency (by crying in your arms, for instance, rather than screaming on the shop floor :) ) But it takes time. Also, at the beginning, it may well increase the number of tantrums, it did in our case. But I was now immune to tantrums and whines - they no longer got me angry. And thus i have been able to seek the little person underneath the strong feelings. It has given me a huge freedom, to deal with my sons in this accepting and loving way. Shouting is still heard in our household but its tone is jokey rather than angry...
Hope you will all find the solutions you need.
M