Short period cycles

Tomeka
I'm 36 and have been on birth control (BC) since I was 19 years old. I stop taking my BC a year ago when I was 35. While on BC my period cycle has always been 3 days. Once I stop taking my BC I immediately came on my period the following month and my period days range from 3 to 4 days long with 24 to 26 cycle days each month. This app is saying I have irregular periods and I'm very nerves because I'm now TTC. I would appreciate any insight on my issue. Thanks