Your boyfriend cannot enter you fully when in missionary as there seems to be a blockage or lump but when im on top its fine?

it is because your boydriends penis is either to big for you vagina, or you tensing.. you have to relax, let him slowelt touch your clitoris. this will help you loosen up and the "lump" you are feeling is the knob of his penis. this may not sound what it feels like,

if you want to loosen yourself quickly then flick your clitoris and rub the lips of the vagina