whats wrong with me?!

After 2.5 years of being on mirena I got it out at the end of August. I got a period for the first time a week later. We've been TTC since. My 2nd period was 5.5 weeks after the first one. Just got my 3rd period 5 days before expected. Clearly my periods arent consistent yet so I dont think this app is predicting my ovulation right... can I even get pregnant if Im not regular? Im so disappointed since Ive been so nauseous and swore this was our month. uhg..