This is perfectly normal. The purpose of the mucous is to keep the vagina clean through discharge and to help the penis slide in and help the sperm swim up. I thought I was having unnatural amounts of discharge when I was younger too but it's either gotten a little lighter as I've gotten older or my birth control is drying me out more than I thought. You will have discharge until you go through menopause.
This is only unnatural if the discharge is yellow or green like pus and smells bad (like nasty, not musky)-- that indicates a yeast infection.
If you're sexually active with your boyfriend, you shouldn't be embarrassed about it because there's nothing worse than vaginal dryness during sex (think sandpaper). He probably isn't even aware of it and it's making things more comfortable for you in the long run. If you still aren't happy with that, just wash up in the shower before you go see him and that will take clear mess from your entrance (washing gently before and after sex can also reduce your risk of urinary tract infection).
And if you're sexually active with your boyfriend, always remember to use protection!
23 years old-- shared the same insecurities as a teen