Lactating without pregnancy?

Ana

Hello! Last Sunday morning I took a shower and thought I saw something come out of my nipple. Later that night I squeezed both my breasts and saw a milky substance come out. My daughter is 3 and a half and I last breastfed her when she was 5 months old. My current partner and I have been trying for a baby. On Tuesday I took the first response 6 dpo early testing which gave me two negative lines. I took a digital first response test yesterday that stated I was not pregnant. I have this app and stardust to track my cycles. On this app it says I’m five days late and stardust says I’m 8 days late. My breast do feel more full and heavier. The veins are more pronounced and my areola seems to be getting bigger. Normally if my period were coming I’d be moody and uncomfortable. But I’ve been feeling great and have this sort of high. However my partner has been nauseous, craving food, and emotional which is unlike him. I guess I’m asking if anyone has experienced anything similar because I can’t seem to figure out what’s going on if the tests are negative. TIA!