To the OP, I am curious about your boyfriend? Is he also Catholic? If he is not Catholic and not respectful to our religious beliefs, then I would strongly encourage you to take stock of this relationship and consider ending it permanently - such a relationship will only bear bad fruit.
I understand how hard it is to be pure, I am engaged and me and my fiancée do go to confession occasionally because we goofed up. There was a time not long ago we almost fornicated, we both felt terrible afterwards. We went the confession and boy, did the priest confirm the gravity of the seriousness of our sin by what he told us in the confessional and the penance he assigned us to do before he gave us absolution.
Another time when we confessed to being impure, we were told to avoid kisses on the mouth until we’re married. In the meantime, do kisses on the cheek or hand. It’s hard yes, but we both know this is for our own good! When we’re both married, then we can enjoy the pleasures and wonders of sex (and only with a willingness to be open to the conception of new life).
Remember, sex is a most beautiful gift from God, and He wants us to enjoy this gift in the proper manner. Sex is so powerful because when we make love we are imitating God in the most intimate way possible, because it is through the act of sex we create new life! God loves us so much he chose to share his awesome power of creation with us! How wonderful of a gift is that!?
It is no wonder the devil seeks to pervert human sexuality and marriage, because these are most holy to God!
Sins against purity are very serious. If memory serves, Our Lady of Fatima said more souls go to hell for sins committed against purity than any other sin.
Remember, you hear the words of Christ through the lips of the priest. God is a strict and loving father to us, and only wants what is best for us.
As for what you were told in the confessional, this may also be a test for your relationship to see if it is truly love or lust.
If you two are both Catholic and are practicing, maybe this is a good time to discern marriage with each other? Remember, for us Catholics the purpose of dating/courting is to discern our possible calling to the vocation of marriage.
If this man is not Catholic, or is not a practicing one, perhaps this may be a wake up call for him to repent? Remember when Our Lord proclaimed the Kingdom of God and called on sinners to repent and do penance?
All in all, if your boyfriend isn’t Catholic, and won’t respect Catholic beliefs, I would seriously consider ending the relationship permanently as it is not good for your spiritual health. If he is Catholic, you both need to follow the instructions you received in confession.