9 days for KL + Singapore, is it too much? In an anxiety spiral right after booking & need reassurance!

Hey everyone! My partner and I just booked a 9-night/10-day trip for early February (Arriving in Kuala Lumpur, departing from Singapore). This will be our very first time in Asia!

Right after booking, I got into a massive anxiety spiral and buyer's remorse reading online itineraries where people call these two cities "boring," "sterile," or claim "you only need 2 days each, then get out." Now I'm spiraling thinking we made a huge mistake with the duration, and even booking this whole trip to begin with. It all started with us finding a good deal for Malaysia tickets (and then we decided to pay a bit more to return from Singapore, which has made me spiral even more!).

As a sociolinguist, I have long been fascinated by Singlish and the unique linguistic tapestry of the region. But I am terrified that I’m dragging my husband along just for my own niche fascination, that he will find this entire experience boring, and that we paid way too much just for this.

So far, we have mostly traveled around Europe. We are not big on historical museums, but we are both fascinated by architecture (both modern and historic), developed urban spaces, and good food. Coming from a developing country, we actually genuinely enjoy clean, hyper-developed, safe, and modern urban infrastructure (which is why we aren't looking to add rustic backpacking spots like Cameron Highlands or Taman Negara).

The Split: 4 nights in KL + 5 nights in Singapore.
Please tell me: Is 9 nights actually a solid duration to decompress and explore without rushing, or should we add another spot to make this whole trip worth it? Any tips or recommendations to put my mind at ease? Thanks!