Congratulations for recognizing and admitting to your own insecurity. A lesser man would just project onto his partner, thinking badly of her just because she is interested in using a dildo.


By all means explore the use of the dildo together. She can also use it alone of course.


So many men make the simple error of judgment that size is what really matters, though I would wager a guess that if you ask them what size, they could not actually tell you. Perhaps they would just say, bigger than I am. What really matters is a match between the woman and the man. One aspect of a match, the ideal aspect, would be if the size the man's lingam was exactly the size of the woman's vagina. This is a nice bonus if you happen to have that, but I don't know of anyone who ever put that as a requirement for relationship happiness.
 

The more important meaning of a match between a man and woman regarding genital size, is how they match up whatever the sizes are. For example, if the man is small and the woman large, you want to use positions for sexual intercourse that allow deep penetration. Also, it would be very important to make sure the woman has one or even better, a number of clitoral orgasms, before there is any penetration with the penis. Once a woman has had one or more clitoral orgasms, the entire vaginal canal becomes awakened to orgasm, including the g-spot, but also any number of other sensitive spots anywhere within the vaginal canal.


Regarding the g-spot, you probably already know that it is located only approximately 1-2 inches inside the vaginal canal, so even the shortest penis on record would reach it with the proper angle. So use sexual intercourse positions that put you into contact with the g-spot.


Then there is pleasuring her with your fingers, and of course your mouth. Learning how to touch her properly with your fingers and learning the fine art of cunnilingus (oral sex), you can bring her to have many orgasms including clitoral, g-spot and other deep vaginal orgasms and ejaculatory orgasms, without ever penetrating her with your penis. The use of a dildo is only an additional way to pleasure her, i.e., if you insert the dildo for her.


If you have learned the skills of a great lover, and have mastered your ejaculation response, i.e., learned how to make ejaculation voluntary so you only ejaculate when you are both ready, then the size of your penis will be understood to be of little concern.


I hope you get the idea by now, it is how you use what you have rather than how much you have. Even more important than that, it is most fundamentally about emotional connection, being fully present in the now moment during lovemaking (not in your head worrying about the size of your penis), giving and receiving pleasure, and about freely and unconditionally giving and receiving love.