Hi im a very worried mum of a 19 year old daughter she had sex 2 weeks ago and has a very s hort2 day period last week which was worrying coz her periods usually last 4 to 5 days she did a test yesterday came up pregnant straight away done more tests negative which is confusing but she now tells me she had unprotected sex last night so could she now be pregnant do we count the last bleed as a period of go from her last one and very confused about tests sorry don't know who else to ask ...advice would be brilliant