This may sound strange so I’m sorry

First my period is bang on 26 days every month but this time round I started af on cd 29 so 3 days late x I had negative on all the tests x anyways my period isint as heavy or painful as usual so I Dec to take a test and there is a big pink line in it ? I def have had loads of negative results but now I’m bleeding enough to fill one pad (not painful at all) I have a big pink postive?