Hello. My Son Was Born Via C-section In March This

Hello. My son was born via c-section in March this year. During the c-section the doctor found a benign dermoid cyst on my left ovary and the ovary was removed. I was still having lochia at my 4 week post-partum check-up. I went on Melodene birth control for 3 months to regulate my periods. Since then my periods have been 26 days apart. Today is the 31st day into my cycle and I have not started my period yet. I have taken 2 pregnancy tests and they were both negative (not even a faint line). This is the first time that my periods have been irregular since, so I am quite worried. I have been having pain around the spot where my remaining ovary is for about 5 weeks. I have a spastic colon, so it could just be from that. Any advice would be appreciated please? Thank you for your time