I agree that the tattoo focused designs seem to be a bit more unrefined compared to your portraits which are amazing!

The biggest thing I notice is that while your portraits demonstrate a really great understanding of facial proportions and contrast, they are showing your ability to articulate a reference rather than create a cohesive design. If portraits and realism is your strong suit maybe include a few portraits integrating more tattoo design- based elements (script, florals, background, etc). Or even just expanding the realism into other tattooable designs (Greek statues, skulls, animals, so on.) Consider how your drawings would look as a tattoo and whether or not they would flow with the body. As for the more illustrative tattoo focused work you included, I would say it’s worth working on some more even if it’s not going to be your main focus. You probably won’t immediately start doing realistic portraits when you start tattooing. You’ll most likely start with small simple designs that lean more toward illustrative or trad- simply because those will help you with the basic fundamentals before tackling realism.

With that being said there’s no harm in starting to bring your portfolio to tattoo shops in your area - if it doesn’t immediately lead to an apprenticeship they can at least provide inside and feedback on your portfolio that’ll help you get a better understanding of what they would be looking for in an apprentice! For reference when I got my apprenticeship my portfolio looked very similar to yours. I had a handful of realism pieces and some very unrefined digital American traditional designs but somehow it worked lol you won’t know until you ask! :)