<human>: Can you condense the text into three sentences or less?

Like the title says, I am concerned I am being too much of a clingy girlfriend. The reason I say this is lately I've noticed I am getting impatient and annoyed when my BF takes a couple hours to reply to my texts and its caused a couple mini arguments so far. 

He doesn't see the not texting back in a timely manner as an issue because A) hes either busy at work or at home doing research (working towards grad school) or B) he rather have me call him to talk anyways. 

The thing is I KNOW I'm being ridiculous but I can't help but feel "hurt" and "annoyed" because he took 3 hours to reply. I would like advice on how to get over this feeling and just accept we don't have to text 24/7. 

Another thing is sometimes he really just can't text me back, as his outdated iPhone has been dropped in water and has a smashed screen and is barely surviving. Unless plugged into a charger it barely last two hours and goes from 100% to 60% with the use of one app and has started to randomly shut off.  So I shouldn't be so annoyed that he takes forever when his phone doesn't even let him! 

For the record he's never called me clingy, but I was like this in my last relationship (in a much more extreme way, got mad after ten minutes of no response) and don't want to ruin this this lovely one with my insecurities again. In a joking way he said I'm "demanding" but I think he was a little serious, I would really like not to be. 

Any advice on this would be appreciated!
<bot>: I get annoyed when BF takes hours to reply to text, he doesn't think its an issue, how do I get over it.