Separation Anxiety but I'm doing all the 'right' steps?

As the title suggests I'm having issues with separation anxiety, I've already read the subreddit right up multiple times on separation anxiety and how to prevent/ train it out. More information on our setup, I am the main care taker of my mini dachshund (16 weeks today) and my fiance is the caretaker while I'm at work 8 hours a day. We have a pretty good routine set up, and I've diligently worked on trying to make sure the puppy doesn't develop separation anxiety, but I feel like I took a wrong turn somewhere because her anxiety is getting worse and worse 😭😭

EVERY SINGLE DAY since 8 weeks old, I take about a half hour to just work on leaving the room and reinforcing no crying if I leave the room and I will always come back, my fiance works from home so she's always with the puppy even if I leave, but the puppy pays her no mind like 90% of the time (causing puppy blues in my fiance but she is trying to get back on board)

In the last 3 weeks, whenever I even walk towards the door, my puppy will start whimpering and whining, and if I leave for more than 5 minutes she's yelping and UGHH I hate hearing her in distress like that 🥺 now I will say she typically settles herself within 3-5 minutes and will find something to do or go to her crate and take a nap. I also do have a decent place and bed command as well as her recall commands are getting pretty strong, wait command is getting better everyday. So I've started making her go to her place when I need to go to the bathroom or something, she will stay in her place right up to when I get out of eyesight or she hears the door open, and she's right back on top of my feet. Then when she puts two and two together that I'm trying to walk out of the room without her, she starts whining and being stubborn about staying in place, knowing darn well I'm about to leave her 🙄 she also recognizes my work uniforms and linked them to leaving so she gets all moody when I get ready for work. I've also put my work uniform on and just never left multiple times but didn't seem to help.

I'm getting overwhelmed with the anxiety, I thought I was taking the right steps to prevent it from day 1 but apparently I messed up somewhere or I just unfortunately made a really co dependent dog. I also make her have independent play time throughout the day, basically I'll just sit in a corner of the room and ignore her while she plays, I try to get as much enrichment activities in as possible, but yeah idk. What am I missing? Did I misread how to tackle separation anxiety and totally boof the training? Is my pup just overly codependent on me even though my fiance is LITERALLY HOME 24/7 WITH HER??? I'm at wits end with this and I'm saving up to afford a behaviorist to come check out the situation but like I said, saving up. Hoping you guys can give me some insights or a new training ritual that I could try unless I'm doing all the right things and just need to keep at it?