Sold my bitcoin and regretting it, advice needed

Back in 2015 I bought a few hundred dollars worth of bitcoin, was planning on buying something with it that only accepted bitcoin. Shortly thereafter I lost/forgot my coinbase password, and just kind of put it out of my mind.

Fast forward to last week, I was doing my taxes and reminded of bitcoin and decided to find out if there was any way I could get into my account. Was able to verify my identity and get in, and to my pleasant surprise I had $23k in my account. I didn’t know anything about what was happening with the market, all I saw was a huge return, consulted a few friends and they said I should sell. So I sold.

I’m now immensely regretting that decision. I didn’t know anything about the upcoming halving, I didn’t research the trends. I’m a complete noob with this stuff. I don’t make a lot of money, about 42k a year, so when I saw the 23k it was more money than I had ever had in one place before.

Should I buy back in, and how should I do it? I know I’m going to have to pay at least 15% tax on what I sold. The price keeps going up. It appears that there is potentially going to be another price surge after this halving that I’ve been reading about, but I know that I have to hold the investment for at least a year to avoid a higher tax rate. I’m just confused and frustrated, and seeking direction. I’ve seen the power of this investment, and want to invest more in my future.