Hi,
Welcome to the forum. I am really glad to help you out. You should ask your partner to indulge in plenty of foreplay as that might help in stimulating you more and facilitating a smooth sexual intercourse and which increases the chances of ejaculation. Moreover, you should drink more fluids daily as the major part of the semen is formed by the prostatic secretions and thus that should also help.
I sincerely hope that helps. Take care.