FWIW, I come about 90% of the time I have PIV sex. However, 100% of my orgasms are from self-stimulation. The only other way is from receiving oral, but my point is that you need to work on this alone for a while, and when you accomplish it, your O's are up to you and you alone. Obviously, teaching your H how you like it is part of that.
Here's what I suggest:
Spend an afternoon daydreaming about things you find erotic. Use your fingers (and some lube or spit) to slowly, gently caress, rub, and wiggle the different parts of your va-jay-jay. When you start to feel that good, special feeling, keep doing THAT. Don't rush and don't have ANY expectations.
If you can do this to fruition and you give yourself an orgasm, then do it a few times more until you get the hang of it. When you do, you can start trying it while having sex with your husband.
If you can't, (and I suggest you try at least few times before giving up), then buy the toy and proceed with the same plan.
Good luck honey!
P.S. pregnant O's are intense! (In a good way)