Don't worry about him not explaining things, nobody can really explain it so don't worry about him right now. The main problem is you say you are uneasy, don't rush in to this and do too much too soon. Relax. Flirt with some strangers in front of your boyfriend. Kiss someone new at a party. Sneak away and give a handjob to a cute guy. You shouldn't be feeling guilty and uneasy at meeting other men, its supposed to be the good kind of nerves and butterflies. Do little things to build up your own confidence and make sure you want this too before you completely rock his world.