My boyfriend loves huge boobs, how do I feel sexy about my b cups?

First of all, I have a great boyfriend it must be said. However, I feel like he doesn't feel a lot of sexy attraction to me, that his past interactions were lustier, and I especially worry my perfectly lovely b-cup breasts disappoint him.
  
I know he's had a history of attraction to and fooling around with big boobs (DD & E cups) from the time he first got his hands on a pair as a teenager to about age 27. I worry he's been conditioned by experience for big boobs to equal lust, no matter her face or the rest of her body or his feelings for her.
   
He was 30 when we got together, and had had a couple of dry years sex-wise before we met.
  
But in messages he wrote to friends (pretty immature bragging messages it must be said) aged 25-27 - before me - he went on about a few girls' big boobs as "epic", "savage" "bad boys" and "massive" and described his excitement about them, what these girls did with their boobs with him and what he did to their boobs. He also wrote "on nom nom" as in yummy. It's like their face or general body shape wasn't a factor, just a nice big pair. Pure lust.
   
Now he's 32, he has low personal energy and headaches. His sex drive is affected - at one point about 5-6 months ago he had low testosterone - and sometimes he needs Viagra because of ED.  It's not me, he had that issue before me.
  
I'd like sex 3-4 times a week. I'm used to at least that much. I'm used to a partner seducing me and initiating sex, but I mostly do that. He seems to feel like it once a week. Sometimes twice, but he has to plan that. He gets tired easily in general. And sex is good, but I feel like he concentrates and doesn't get lost in the moment or with me. Sometimes I wonder if too many years of being solo and wanking to porn made sex more psychological for him. I've seen he still searches big tit porn sometimes.
  
I've also always been used to all my partners being more demonstrably passionate and lusty towards me. It was clear they found me sexy and felt excited to be in bed with an attractive woman. They've made a big fuss over my body and raved about my bum, skin, my general body and told me I was like a work of art, or the most beautiful girl they'd met (sincerely and in an admiring way). I feel like some of my better physical aspects go unappreciated.
  
I feel like sex with me is kind of work to him and I miss male appreciation for me. I'm a pretty blonde who looks much younger than my age, but I need to prompt him to tell me a compliment on being physically attractive. Maybe he thinks that kind of thing is superficial but I like to feel really desired by the man I love. I like feeling like my partner has "scored with a gorgeous woman and he knows it" but he's the one man I've not experienced that with. He loves me, but I don't feel like he's "into me".
  
I also worry my perky b cups will shrink and  sag after our breastfeeding (baby due in February) or get smaller when I shed my baby weight. I used to be slimmer and they were only A cups!
  
I know they're healthy and will probably give our babies nourishment, and I'm grateful for it...
But how can I get over feeling my boobs are really small and unsexy to him? How can I regain my confidence? I never worried over boob size with previous partners or questioned my sexiness. I'm used to having better self esteem sexually.
  
He's an amazing, supportive, caring boyfriend, treats me beautifully, and he's not doing anything wrong. But his preference won't change, so I need to find a way to move past my feelings. I've tried but I'm stuck.
   
I hate feeling like his best sex experiences are past... I dislike feeling insecure, I'm unused to it. He says his energy & wellbeing is improving, but he's said it for over 8 months, so I don't pin my hopes on that anymore 😕