Something similar happens with my wife, although it has nothing to do with toys. She sometimes can get so close to having an orgasm but can't quite get there, and then it's almost like she starts to get numb to further stimulation. What we usually do is slow down and stop directly stimulating her. This lets her come down a little after few minutes, and then we go at it again. This usually works for her.

Are you able to have an orgasm while having sex with him? What techniques work (oral sex, manual stimulation, G Spot stimulation etc?) Maybe a stronger toy would be better. Not all vibrators are created equal.

What toy are you using and how are you using it? Doing what is closest to what brings you to orgasm with your boyfriend is probably the best for you. Or a stronger toy may be in order.

I have to tell you, when our children were young, I entered a phase where all the orgasms I needed were provided by the sex My Man and I had. I didn't masturbate for several years. I had little time, with babies and little children, and we had sex often enough that I didn't feel the need for it. With the exception of pregnancy, when I was horny and we were restricted by high risk pregnancies. (We had not started using toys at this time.) Only when I entered peri-menopause and my sex drive went back up to adolescent levels (My Man says, "It's like being married to a 18 year old boy. Only, you're a chick.") did I feel the need to get myself off on occasion, once again.