This is Lana from Shopify.
I understand what you're saying here, there is always a lot of work involved when first getting set up with your store! In order for us to be able to look into a possible extension of your trial, you will need to contact our support here. The reason that you need to go through that link is because it is not currently possible for us to look into your account details from the Shopify Community.
You mentioned that you need more time because you're still working on your products - what kind of products do you sell? Also, are you having any issues with uploading them to the admin? Just in case, I have guides from our Shopify Help Centre on how to Add and Update products, as well as how to Import Products via CSV Files.
Once you get sorted with your products, you can start looking at other things that you need to prepare for your launch. For this, I recommend you look into our Shopify Blog article on The Store Launch Checklist (2021) which is very thorough and goes through everything you need to do.
Let me know if you have any other questions here at all!