Reverting to one's old habit of haidh

I am writing as I am very confused regarding my Haidh. Before giving birth, my Haidh lasted a week. I had my baby via C-section on 3rd Jan 2017. Bled for 40 days. After that, I considered it Istihaadhah and started reading Salaah. On 22 Feb 2017, I started bleeding again, this time like my normal Haidh. But because there was not a 15 day clean period in between, I continued Salaah. I stopped reading once the 15 days from Nifaas was up and then only considered it a period. The bleeding ended on 9 March 2017. On 19 March 2017, bleeding started. This time also exactly like my Haidh but because 15 days in between hasn't passed, I'm confused. Since the first period after Nifaas wasn't after 15 days of cleanliness, all future calculations are going off. Please advise as I know this is Haidh bleeding but have to continue Salaah each time. Jazaakallah.