Insecure about husband's exes

I was using my husband's laptop and came across a chunk of old pictures that weren't in a folder. Some were of just him, some of his nephew, and some of his long time ex girlfriend and what I assume to be another ex girlfriend. The creation dates were years ago, but they had a "last opened date" in late August of this year, which seemed odd. It's a Mac and it doesn't seem that the open date changes when you actually open the file in Preview, and since the dates are identical, it looks like a batch upload or something. Either way, one of the girls is extremely pretty and very thin. I'm about 5'5" and 140 lbs, which isn't big but it's not tiny either. I have a more muscular/athletic body type, but definitely have cellulite on my thighs I've always been insecure about (even though I know so many women have this). This girl was really thin, had to be about 20 lbs less than me, and was wearing makeup, looking very trendy. I never wear makeup and my husband tells me he likes me without it. He's told me before how he's dated people who wear it and he doesn't like it. I'm also not super into fashion, so far from trendy. I just dont spend money or time on it.

Last weekend we visited some of his friends and he mentioned how thin the wife was. I asked him if he wished I was skinnier and he told me no. He said I was "fine" like I'm okay, not like hot-fine.

After seeing pictures of the kinds of women he's been with, it makes me feel super insecure about how I look. He tells me sometimes that I'm cute or pretty, he always tells me I'm sexy when we have sex, so I know I shouldn't put weight (no pun intended) on his past, because it was before me and therefore should be irrelevant. But it seemed like he was looking at these pictures recently. He does that sometimes where he'll just sit and look at pictures for a while. For the most part, it seems like he really respects boundaries in our relationship, so I trust his behavior.

I guess I'm mostly insecure about his thoughts. Like, does he fantasize about past girlfriends while we are intimate? I've noticed he peruses what seem to be random girls pages on Instagram (guys also though) and I wonder if the girls are people he dated before. Does he wish I looked different? It just makes me feel like I'm not enough somehow.

I'm trying not to add weight to things that mean nothing, but my natural tendency jumps to insecurity. Please help me. Thanks in advance.