You consider her offer for a moment, it's very appealing, you're feeling somewhat turned on from seeing your girlfriends partial erection and you're also curious about how things feel from the other side. Doubly tempted since you literally have her parts and she yours so once you get her dick inside you you'll be feeling what she felt when you had your first time together less than an hour ago. You imagine riding her rock hard cock and feel rush of heat and arousal from your new parts, and realize that you'd be missing something she had...
So before agreeing to her offer you make a wish.
"I wish that you were attracted to breasts the same way a straight man is without changing anything else about your sexual preferences, and that I had breasts that are your ideal shape and size for a partner."
Her eyes widen in surprise, and you feel a surge of pressure on your chest as your breasts grow in. First your nipples grow and change to be decidedly female, then the actual breast tissue underneath begins to expand and quite quickly you can feel the extra weight pulling on your chest. You reach up and cup them as they grow, looking down and watching them. You find yourself getting more turned on watching them grow, you feel a surge of warmth and moisture in your new vagina. The water lends your boobs a small amount of buoyancy and the feel quite a bit heavier as you stand up just as they finish growing.
They've gotten fairly big, bigger than Amanda's not that hers are small. You look over at her, and find she's staring at your chest.
"Hey! I'm up here!" you jokingly say. She turns slightly red and looks at your face.
"Sorry"
"It's OK"
"Why did you do that" she says and her gaze drifts back to your chest, making you fell amused and again slightly turned on.
"Well I didn't really think your experience of sex from a guy's perspective would be complete without you liking boobs, especially since I want to be on top, you'll enjoy the view." You wink at this last part, she blushes again as she realizes she's been staring again. "You're even more distracted by boobs than me!" You say with a grin. You glance down at her crotch and see that she's rock hard now, and on her smaller body your dick look bigger than normal, you feel a new rush of arousal and the strange new physical sensations that having your girlfriends parts brings.
"I'm just not used to it" she retorts. Then giggles. "Besides, you specifically gave yourself boobs that I'd think are perfect. If I had your perfect boobs all of a sudden I don't think you'd have an easy time keeping your eyes off them." As she says this she looks up at your face again, having found that she had let her gaze fall back down to your boobs. "They really do look fantastic on you, and not just in an 'I really like boobs now' way, I mean that way too, but..." She thinks for a moment. "Hmm maybe later we should make it so all men have boobs and women like them..."
You're a bit surprised by this. "I'll have to think about that one, we'll see if I like having them." You turn and climb out of the tub, noticing as you do that apparently your pelvis is a bit differently shaped now, probably comes with having a vagina, and towel yourself off while saying "So is your offer still good? You definitely look ready." You catch your reflection in the mirror, your hips don't really look any wider, but as you move you're definitely aware that your legs are slightly further apart, which makes walking feel a bit strange.
"Huh? What off... Oh! Yeah!" She glances at the mirror and realizes what you meant by 'ready' and blushes again. She climbs out of the tub too. "Wow that feels weird, having that thing sicking out and moving around."
"Yeah, having your parts doesn't feel any less weird to me either"
"I bet you like that view now though." She grins at you as you turn back towards her and toss a towel to her. Her gaze drifts back to your boobs as she starts drying her hair.
"Uhm... Well..." You stutter.
"Awe come on, I know you've got my preferences when it comes to between the legs and I certainly liked it earlier."
"OK, you got me. I like the way your dick looks." She grins at you.
"I bet you'd like to do more than look." She takes a few quick steps up to you and puts her arms around you and pulls you into a kiss. You feel her boobs pressed against yours. Normally the feeling of her boobs against you is something you quite enjoy, now it's much more so. You feel your nipples tighten and stand up, the pressure and slight movement feels good, your boobs seem to be very sensitive. She presses her body close to you, and you feel her hard on against your leg, and a thrill of arousal shoots through you again. You return the embrace and the kiss.
After a moment the kiss breaks and you hold each other looking into her eyes. You feel a dribble of your juices run down your leg.