Forgiveness Gate is open for all the believers in Allah who committed sinful acts as far as they did not reach to dying situation. Allah (SWT) loves those who repent and sincerely decide not to continue sinning and seek forgiveness. The Hadeeth Qudsi reported the Allah says: I love those who repent their sins and leave and my love is more to the young person who sincerely repents his sins and decides not to commit is again.
There is no question of feeling ashamed as far as you are really repenting and sincerely doing your best to make up what you have missed.
Do your best to fulfill the obligatory worship and trust the Allah is The Most Merciful and The Best Forgiver.
Those who are not sure and don't care for leaving the sinful acts and making up the missed worship should feel ashamed.
May Allah (SWT) protect all of us from any sinful act.