Haram to fast last days of Shaban for a purpose?

Salam Aleikom. I accidentally fasted voluntarily on a sunday the last half of Shaban even though it's considered haram/makruh. Someone informed me of the hadith that you shall not fast unless you used to do it. I didn't found out it was sahih until iftar. There's also a hadith you cant fast solely on a friday, saturday (Both hadith are considered authentic). And Sunday is the christians day. I knew the later hadith before hand. Now do I have to not fast in the last half of Shaban because it's considered haram or continue the plan I had to fast Monday because I fasted Sunday alone? If this happens do we have to follow the hadith which says it's haram or go with the hadith that says fast another day after only fasting Friday/Saturday?