Testing

Has anyone gotten a positive test a week after period is due I was on Baby med and it had said I would of had implantation on the 18th which was 5 days before my period was supposed to start I started spotting on the 17th it lasted 3 days no clotting and very light I took a test again today and nothing I've been tired ,nassous and have had achy breast if I am pregnant baby med said I'd be 4 weeks 3 days shouldnt I be able to get a positive test by now help I feel like I'm losing my mind