what i don't quite get

I'm going through a study right now - Beth Moore's, Believing God - and there's something that's been puzzling me of late. One of the things she talked about a couple weeks back was the idea of transgression vs. sin. What I love about this study is that Beth always gives the original definitions...the Greek or the Hebrew...which help me to understand what these words mean. I mean, wouldn't you think that transgression and sin meant the same thing? What I learned is that the word transgression generally means sin that is pre-meditated and willful. In other words, sinning on purpose just because I want to. Sin, on the other hand, is generally referring to sin in general and usually what is not done with a rebellious spirit. So here's where I'm puzzled...
Psalm 32:5 - Then I acknowledged my sin to you and did not cover up my iniquity. I said, "I will confess my transgressions to the LORD "— and you forgave the guilt of my sin.
How crazy is it that my sins...even the ones that are pre-meditated and willfully done...are covered by the blood of Christ? I cannot understand how God has the patience or the heart for that. It boggles my mind that God would love me enough to willingly forgive me when I confess everything to Him...especially when He knows I'm going to do it again. Unbelievable...and yet what an amazing gift I've been given. I get to choose daily to walk a blameless life. Not perfect, just making the choice to stay away from pre-meditated sin. I'm going to sin, but I don't have to plan out how I'm going to do it...and if I make the choice to sin "because I want to" I'm thankful that God will forgive me when I truly acknowledge that sin and don't try to hide it from Him. And yet, sometimes I wonder, how many times will He forgive me before He decides He's had enough. I pray I never get to that point.