Assurance

So, I’m interested in becoming part of the Lutheran church specifically the LCMS or WELS branch. I’m struggling to find some doctrines on whether one can have assurance even though they struggle mightily with sin. I struggle a lot especially with anger, pride, lust, and I’m certainly way too lazy. I’ve heard about the comforting doctrines of assurance in Lutheranism, but I’m wondering if that applies to such a wretched sinner like myself. I still don’t really understand repentance to be honest. I’ve seen so many different definitions. I confess and run to the Lord for mercy that is only available through Christ’s finished work, however, I’m hoping I’m not deceiving myself due to my sinful habits. Lord have mercy on me a sinner.