3 Pos preg tests one after the other what are the chances they are false?

Hey so after 8 month i finally hae a BFP!!! x3 of them!!! . Firstly I taken two pound shop ones they come back almost instantly pos so I told my DH so we ran to boots to get a digi and that was pregnant too!!. The only thing is I hae period cramps sharp ones on and off and im so scared im going to misscarry or its a false what are the chances they arefalse i did one after the other