Unfortunately, it's not okay. A wrong sized contact lens will not only cause discomfort but it can cause some serious problems to the surface of your eye. If the size is different, the contacts can either be too steep or too flat. This compromises the fit of your contact lenses. Therefore, it can move excessively, which rubs off the cells on the front of your eyes. On the other extreme, it can hug your eye too tightly and badly affects the layer of tears to fully cover your eyes. This causes your eyes to swell and makes your vision hazy.
Wrong size contacts may cause blurry vision, discomfort, and corneal ulcers, so you'd better take care of it
My recommendations: If you have a pair of glasses, you might use them for the time being until you change your contacts. It's necessary that you learn to keep away from lenses for at least some time.
Of course, it is not okay if you wear wrong sized contact lenses. The right size of contact lenses in the first place ensures your wearing comfort, so once they come in wrong size, it will not only compromise your wearing comfort but also will do damage to your pupils. It all has to do with the different base curve which comes in too steep or too flat. In the case of too steep, the contact lenses will closely attach to your eyes so much so that it will impact the tears lubricating your eyes. Otherwise, if too flat, the lenses will move freely. To cap it all, corneal ulcers may even occur as a result of it. You had better try on the properly-sized contact lenses that fit. By the way, buy those brand contact lenses from the optometrist's.
Well, yes, it will make your eyes feel uncomfortable in your eyes if you have the wrong size of contact lens. In fact, when you have contact lens, professional person will give some eye exam, and then choose the right size of contact lens for you. If you wear the wrong ones, the most common symptom for your eyes will be blurry vision. And also, for some people, itchy eyes can be possible. So that is why you have felt itchy eyes. Anyway, you should have right sizes.