For those of you that got pregnant while breastfeeding, how long did you continue to breastfeed? Did you have supply issue? How did you know it was time to stop? And how did you do it, cold turkey?

My 5 month old isnt getting full on my milk alone anymore and i dont seem to be producting much lately. It also feels like she is starting to reject my milk lately and prefers formula. Im only 16w pregnant so i dont think my milk has swirched over to colostrum yet