I think I may not have phrased my question properly.
Since coming back to the church I have looked at various examinations of conscience, lists of mortal sins etc. Indeed at that time there were many things that I was not aware that were mortal sins.
However, it seems that the better I acquaint myself with this the more confused I get.
I understand that there are some sins that are always grave matter e.g. missing mass on Sunday without a valid reason, and that there are many (in fact probably most) sins that may be venial or mortal depending on the gravity. A good example is the current thread about gluttony.
My problem is that while I understand the theory of the 3 conditions for grave matter, it’s the practical application of them that gives me a problem.
Many people on this site have said that while you might not be aware that something is grave matter, you would always be aware that you are committing a mortal sin, due to the condition of sufficient reflection.
A simple definition seems to be that if you knowingly and willingly do something that you know to be serious (grave matter) then it is a mortal sin. Based on this, it would seem that mortal sins are quite difficult to commit and that there would be no doubt.
My problem is that I tend to worry that everything i do is a mortal sin.
The question I was asking was does sufficient reflection mean that you have thought about the act (even momentarily), realised the gravity of the act and done it anyhow (knowing you are committing mortal sin), or does a nagging feeling at the back of your mind that you are doing something wrong suffice.
The reason I am asking this is that I always thought that mortal sins were quite rare and that if you obey the obvious rules that you should be fine. However, there is often a lot of discussion on this site about mortal sin, leading me to believe they are more common than I think.