Reading becomes easier in time. Keep in mind that your best practice can be accomplished away from your instrument. You can run notes, scales and patterns through your head while lying in bed, driving, eating, lounging, sitting in a waiting room, etcetera. There is hardly a moment that I don't run a lick through my mind in several keys.
Reading is a combination of knowing the notes on the page without thought and your hands being comfortable with your instrument that they go to the correct notes without thought. Thirdly, having knowledge of music theory is very helpful. You need to be able to look at a page and know chords and scales - again, without thought. You should be able to see patterns and just know what they are. Like technique, most of making music is knowledge, not practice. You don't need to practice reading a newspaper because you've already mastered the alphabet. Theory is the alphabet of music.
There are two ways to memorize. The first isn't memorization but rote. Play a piece 200 times and your muscle memory will sort of remember what to do. The plight of this method is that if you don't play the song for a while, you will forget it. Also, while in performance, if you get off track, you won't know how to get back.
The best, safest and surest way to memorize is, again, away from your instrument. With your knowledge of music theory, study the score, make a mental image of the notes in your head. Analyze the chord progressions, they are very repetitive and often predictable. Memorize the patterns and basic melodic structure. Does it start on the fifth, go to the third, then but to the sixth . . .
The third way is not to memorize at all but, study music theory. Here is a basic example. I mean, HEAR is a basic example. You can probably recite to me the story of Goldilocks and the three bears. You don't have it memorized but know the basic layout and can fake the story. Music is much the same. If you can hear it, and know your intervals, you can "read" the notes in your mind. Mary Had A Little Lamb, for instance. I know it starts on the third because I can hear it in my head as being the third. So, the melody is:
3212333 222 355 3212333322321
Because I can hear those numbers in my head, I can "read" the song in any key and never make a mistake or have to guess a note. With practice, you can even do this with more complicated music such as fugues and other classical literature.