Hi,
I suggest making an appointment with your GP or gynecologist for a pelvic exam to figure out what the cause is. Pain plus bleeding (post coital) shouldn't be considered normal. If you believe you have a tear, you'll want to have that looked at by a doctor before any further damage happens, and to prevent any possible infection.
Take Care
Obviously I would try slow insertion (you probably already know that). You could also ramp up to his penis by trying a little fingering/foreplay before hand, then maybe a toy!? Also consider some different or alternate positions for intercourse. I know sometimes the knees to chest method can be helpful. Plus you have to relax yourself mentally and physically too. If you are anticipating pain you will inadvertently be flex and contracting muscles and you don't want that. Deep slow breaths, loving gazes, and have fun. If all else fails there is still plenty of fun to be hand so try not to stress.