Not getting pregnant because of breastfeeding?

I have a 1 year and 7 (almost 8) month old son.

My period came back quite soon after birth and was regular. Until I got pregnant 1 year after my first was born.

Unfortunately it didn't last long, and I had a misscarriage...

We've been trying since, but my cycle has been very irregular... 26-44 days, 6-11 day lutheal phase ovulation on day 14-30.

I have been to my dr's office, he said it's most likely due to me still breastfeeding. But my cycle WAS regular for a year! And I did get pregnant.... I don't understand 😓

I am slowly decreasing the ammount of feeding, I now feed 2 times a day, yesterday even just once.

My heart aches with the idea of cometely quiting. But I also really want a seconde baby, a little brother or sister...

Can breastfeeding be the problem of not being able to get pregnant? Even tough I allready got pregnant once?