I started playing bass in exactly the same way as you, the first time was banging away endless amounts of open E in a metal band at their weekly rehearals following a drunken conversation a couple of days before. I learnt how to blag my way through their setlist and am certain that what I played was nothing like the original recordings but it fitted. A few books were purchased and a couple of chapters read before they were put down for being too boring, endless internet searches for sites giving free bass lessons were made and some knowledge was gained. 3 years late my style of play has change totally and I had my first lesson about 8 weeks ago. This has led to more melodic noodling around. And all this started on the wrong side of 40. Confidence has been a major stumbling block at times with a big fear of band mates thinking that I'm not really a musician and just someone who is blagging it - but that is only MY perception.
The reason for sharing this is so that you know that there are others of us in the bass playing community who struggle and sometimes it feels like pushing water uphill but keep at it. Yes it does get demoralising at times but all the hard work does eventually pay off.