Hi HES246! Congrats on getting the largest dilator in – that’s a huge accomplishment. Is it a sharp pain or more of an ache or a discomfort? The first part of the insertion is always the hardest because of the tight layer of muscle just inside the entrance, which is what tenses when you have vaginismus and try to insert something. If the pain is more of a dull ache or a discomfort, that will probably get better with time.
The hardest thing about switching from dilating to intercourse is the shift in how much control you have over penetration. There’s two good ways of making that transition easier: the first is to choose the sex position you try so that you have the most control possible (woman on top is good for that). The other is to practice having your partner insert the dilators so you can get accustomed to not being the one to penetrate yourself. Start with a smaller dilator so that you know it’ll go in and you’re familiar with the sensation of it being inserted normally. Both of these techniques helped me a lot and hopefully they’ll work for you too!