What does this mean?

I’m 6 months pp with my first and my Husband and I haven’t been particularly careful. It took us 3 and a half years to conceive our son so I don’t think we’re a very fertile coupling, for whatever reasons. We haven’t been careful having sex pp and I’ve had no symptoms of pregnancy. But I think I’ve definitely been ovulating. I’m still breastfeeding and I haven’t had a period yet since before my first pregnancy. I decided to do a test yesterday morning and then had to leave the house in a rush. I looked at the test after 30 seconds and had to leave. My husband then texts me 4 hours later, “was this test positive when you took it?” I said, “eh? It wasn’t positive?”. He says,” yes it is, but if it’s been left longer than 10 minutes you disregard the results”. So I told him I had to rush out and didn’t check back after 30 seconds ish. I retook a test this morning and don’t think I can see a line (bottom test). But why would there be a line on the first test (top test) if I wasn’t pregnant?