I sent 50 worth of btc to a site but almost 12 hours and not yet confirmed. Not even one confirmation so decided again to send 50 dollars worth of btc to other site and still unconfirmed in my wallet . I tried the 3rd time a 100 dollar bitcoin to an exchange but i see in my multibit wallet it still unconfirmed and not even 1 confirmation. Is there a possibility that my btc will be stucked and i lose all those btc? Is there a difference if i use the core wallet or other than multibit? thank you