If all surgery heal that quick, it's realistic to assume the final bottom surgery was already done and Andrew just doesn't remember it as some memory is still missing.
If you mean there's another hospital visit during the time that we're still missing... that's possible. But the comic was (weirdly) explicit that the last surgery was some kind of advanced prosthetic. Though his balls are gone, so it does rather feel like a distinction with no difference,
I would argue though that in "present" time, Elena has twice on screen had an opportunity to play with her vagina, and we've skirted the issue both times. First was when Andrew first "woke back up", and the next was when having sex with Nikos. Especially the sex with Nikos part, I always assumed there was something more than "Nikos is into anal" at play. Like, we're told the prosthetic has a limited depth, so maybe Nikos finds that unsatisfying or something.
That's the point I was trying to make in that final alinea and took the hair growth as an indicator time passed. One way or an other, Elena has sensitivity to the touch when touching her vagina, so logic says it can't be a prothesis.
I'd argue that Elena also keeps talking about how good anal sex felt, and we're basically told in the dream sequence is a lot of her feelings/thoughts are her playing the character. Again, it's entirely possible that there's been another hospital scene in our missing time. But I think it's equally possible one of three things:
1) The "advanced" prosthetics does transmit sensation.
2) Elena only played with her labia lips, not fully inserted her finger. It's possible that she wasn't stimulating the prosthetic, just her own flesh that's attached to the prosthetic. And had she inserted her finger further, she would have reached the prosthetic.
3) She wasn't actually feeling anything, but like her inability to speak English, she's conditioned herself to
believe she can feel
her vagina.
Like I said, a lot of this might be distinction with no difference, but I do think it's been purposeful that she hasn't penetrated her vagina yet. Whether that's thematically to keep her "virginal" until the wedding, or if it serves as a final bit of feminization, who knows.
Regarding the discussion on preferences on how stories handle "bottom surgery", for me I just want the story to not forget about what they have. If the character is wearing a cage, then that shouldn't be a "one and done". It should be something that maybe they get used to, but still is distracting, frustrating, and maybe even comforting or arousing. Their mentality and behavior should have some kind of response. And, imo, it really should affect the kind of outfits they can pull off. From personal experience, yes: it's possible to hide the bulge of a chastity cage in a pair of tight but stiff fabric, like a pair of skinny jeans. But under a pencil skirt or pair of leggings? Forget about it. I always find going "instantly bulgeless" due to a chastity cage an annoying development. Realism aside, it just feels like too quick a shortcut and often is accompanied by the author just kind of forgetting that the character still has a penis.
Also, I wish stories would mix it up a bit. If you're gonna tuck or cage the penis and then pretend it's not there, why not start with some kind of bottom surgery first then? Especially with the more sci-fi/magic type story progression, not every story has to go: makeup on face to pass, exercise and get thin, start growing boobs, get bottom surgery in last two pages and story done.