Hi po! Honestly, 11 days delay is possible na mabuntis especially kung may contact kayo kahit may condom, pero mas importante na makita ng doctor para sure at ma-check kung okay ka, delayed period pwede ring dahil sa stress, hormonal changes, or kahit adjusted pa lang ang cycle mo after giving birth pa lang last year. Try magpa-pregnancy test muna para sa peace of mind, then mag-visit sa OB para ma-confirm at ma-guide ka properly, lalo na first contact lang after delivery. Marami sa amin experienced delayed period pa even after protected contact, pero ang best talaga ay makuha ang professional opinion mo para walang alalahanin