You're likely falling asleep because you're exercising your brain in a way it's not used to. It should get better as you go. The same thing happened to me when I got back into reading and then again when I started reading regularly in French. And both times it slowly went away as I kept reading.

I break it down to multiple smaller reading sessions a day. Say it's 300 page book and I have to/want to be done it in 5 days, I'd read 30 pages twice a day or 20 pages 3 times a day. It's usually not too annoying reading that little at a time and the book still gets finished quickly.

I figured out how much I needed to read each day for my assigned reading to get it done on time. I always read what I had to for the assigned reading first, but once I reached my daily quota I could read whatever I wanted without stress.

Don't know if that would work for you or not, but I know it worked well for me.

For ebooks, try reading in dark mode if it's an option, and turn off the Internet on the device you're reading on. It will help you focus better and be less distracted.

For audiobooks, try doing something while listening. I find crafts or jigsaw puzzles help me focus while I listen otherwise I have trouble too.

I use it to keep track of what books I've read and save books I think look interesting that I might want to read. Not much else really but I do find their shelf feature useful for organizing books in my to-read list.

I've mostly found their recommendation algorithm to be pretty useless. Though I have heard Storygraph is better on that front.

I mostly read digitally so I'll highlight or bookmark parts I find interesting or think I'll want to find again. Otherwise I just read it like any other book. I don't usually have a hard time remembering what's in a book and generally find it easy enough to go back and look up details if I need to. which I do do every once in a while.

The rule I usually see for when you're reading in a second language is if you come across the same word you don't know five times, look it up. It's obviously important to the story and you'll be more likely to remember it. Otherwise it's better to absorb new words unconsciously by seeing them used in context. Read enough and you'll learn them naturally.

If you like classics at all you can download a lot for free from sites like Gutenberg.

This isn't one I do but both Kobo and Kindle also have a monthly subscription service where you get access to a lot of books. It might depend what kind of books you like but I know some people who get a lot of books that way.

Keep an eye out for sales. I'm subscribed to Kobo's email newsletters. A lot of books on my reading list have gone on sale for really cheap and I found out because of those newsletters. A lot of big bestsellers go on sale eventually too.

Are there any Little Libraries around where you live? There's one beside where I live and I've found a lot of really interesting books checking it semi regularly.

It takes more concentration to follow audio in a second language even if you can understand it all. I don't know why it works that way but I'm a native English speaker and went through the same thing with French podcasts. Start with audiobooks of books you've read before so if you miss a chunk you won't be lost, it'll get easier to follow as you go.