when you find a heartbeat, check your pulse at the same time. If its twice as quick than your own its baby's, and if it matches your pulse it would be yours via the placenta. If you time for a minute it should be upwards of 120 bpm. the wooshing sound can be a mix of baby moving and the placenta so all good sounds. As puddy said it is early, but it could well be. if no luck, try again in a week or two. Dont panic though, as i said before it takes lots of practise, and its early days, also a full bladder helps!xx