Missed Period?! Help Me!!

Rhiannon♡ • ♡♡ Im 22 years old! I have 3 beautiful little boys! Leo 06/06/2012, Lloyd 19/04/2013, Taylah 26/06/2017! I love my little family loads!♡♡
Hi guys im 19years old already got two little boys with previous partners but ive been with my new partner nearly 2 years now and I havent got pregnant but I have been missing periods for a while due to stress but recently I havent been so im unsure on how I have missed my period? Done loads of tests all negative im really scared as I dont want anything to happen? Please help!!!