My sister knew she was pg but the positive test didn't happen until she was nearly 7 weeks pregnant. Loads of tests, all negative until then. Dn now 18 months, gorgeous :)
I am now in a similar position- pretty sure I am, now 6 days late which is v v rare and "feel" pg which is lovely. But no Bfp, which is not! Already have 2 dc.
Anyone else had to wait ages?