ive not been able to get inside her 3 times now, how do i?

We both love eachother but every time ive tried going inside her theres been trouble. I do have a little troubel with premature ejactulation but still, even after that i get hard, and it still doesnt work. Idk if its just that we dont know how it works or if we need to invest in lube. really would appreciate some help here as i genuinely do love her an ik she loves me too