Hi newbie – speaking as someone who used to have vaginismus and dilated (and who now just has intercourse without dilation), this is definitely normal. When my partner and I have intercourse the first thrust has the most resistance and then subsequent movements are smoother. It’s just your vagina stretching and making room. Also, the area right inside the vagina is the tight muscular “wall” you have to bypass anyway, so that will always be where you feel the most resistance (whereas once you get past this part of the muscle, the rest of a dilator will usually slide in easily).
It’s hard to know when you first start dilating how it’s supposed to feel, but it sounds like you’re making great progress. You’ll likely grow used to these sensations over time as you recognize them as increasingly normal.