Help!!!! No period only three months postpartum

Please tell me it’s normal to miss a period after delivering and breastfeeding. First month after delivering I bled like normal second month had a period and it was quite heavy. I thought I had to go to the emergency room, but after calling my doctor she assured me it was normal. Now, three months postpartum and NO PERIOD. Could I be pregnant or is it normal to miss a period while breastfeeding . I will say this I’m not solely breastfeeding. My three month old is on a hypoallergenic formula because he has protein sensitivity so I breastfeed once a day so when I saw my period last month I wasn’t surprised because I figured my hormones weren’t that high to keep it at bay. The day my cycle was supposed to start I got brown spotting, but DH and I had sex the day before so I figured that it might just be vaginal irritation from passionate intercourse. But, then when it never progressed into a full on period I got worried. All this happened the third of this month and still no sign of Aunt Flo. Could I be pregnant? He’s been pulling out when he orgasm but I’m not on birth control nor have I been using protection. Scared AF. If I’m not will definitely be using a condom from here on out. Ladies, is it possible to get pregnant while breastfeeding? Has it happened to you or anyone you know thoughts please