If your boyfriend has a good work ethic and is able to commit himself to things, this may be an indication that he is ready for marriage. If he can't get himself together, your marriage isn't going to help him get himself together. Be with someone who encourages you to be better, not someone who drags you down.
The best advice here is to “trust the gut” and ask others who care about you and your partner. If your gut seems to tell you that you tend to mother your partner, you may want to consider his maturity level. Similarly, if your friends indicate that your partner is lacking good judgement, you should pause and consider if moving forward with the relationship is warranted. However, a boyfriend who is responsible, respectful, communicative, and fully engaged in the relationship may be ready for the marital plunge. Are you? Make sure you have a good handle on your readiness as you parse your partner’s readiness.