Pregnant after FET cramps and spotting

I have just found out I was pregnant on Friday (17th) after 3 years of trying. I have had 1 failed <a href="">IVF</a> and this was my first FET. I have taken two tests that have shown positive results however my official test day is Friday (24th). This weekend I have had small cramps and yesterday I had some light brown spotting however it hasn't got any worse. Has anyone else experienced this? I am worried because Iv tested early and it could be a chemical pregnancy!