tbh your vagina shouldnt have a problem babys come out of there they are designed to strech around pretty much the size of a babys head and it streches back
but maybe you have a problem check with your doctor and see what he can suggest
and try water based lubricants there slippery as hell and will defanatly go in easier as it just stupidly slippy and doesnt soak up i once slipped on it before lol good luck x