@Matildabikini lovely website and products.
I'm not an SEO expert but I woud say you need to do some keyword research to find some longer tail keywords to use in your SEO meta titles and descriptions. If you're using Google Ads then looking at your search queries will help you find new terms. Or set up a free Google Ads account and use the keyword planner - the search volumes aren't very detailed if you're not spending, but it's a start. Trying to rank for 'bikini' is going to be very hard to start with - you need phrases that have lower search volume and so less competition.
I'm not sure what free keywords tools are available now but keywordtool.io used to be good.
Hope that helps
If your website is doing fairly well, can you find the most effective marketing channels and make a bigger bet on them?
SEO takes a lot of time to generate content in order to move up your search position. It's very hard to create a website and the search position will be on the top 10 immediately unless you're targeting niche keywords. I will suggest you do the following:
1. find out the niche keyword with keyword research like "triangle bikini". The key is to find a keyword with search volume between a thousand to several thousand per month. The CPC is not too low. Otherwise, it indicates a low intent to buy
2. create content around the keywords, like youtube ad videos, blog posts, pinterest board, etc. If you create content in external sites, it can drive traffic and create backlink to your store at the same time
3. measure the traffic from external sites and iterate again