Maybe you just need a second or a third round... When you have sex, do you do it earlier than your regular go to sleep schedule. For a while I was dating someone who was used to go to bed around 10pm. I am more a 2-3 am guy. So it didn't bother me to join her, have a good time, and get back to my occupations after she fall asleep. In the morning, it was the reverse. She was getting up around 7am and joining me back around 10am so we could start the day together...
Wow sounds like exactly the routine I had with my ex, her preference was for action before sleep. Her bedtime not mine.
MCTJ or whomever is OP as someone who's struggled with sleep his whole life it is pretty complex and honestly while blowing your load can help it's not the most important factor.
Check your caffeine intake, it has a pretty wicked half life I'd suggest avoiding caffeine after 2pm or have a cup of black tea instead (yes still caffeine but less than a cup of Joe). diet how late you eat, getting in some exercise even it it's just a brisk walk or whatever...yes even an intense sex session isn't the same.
Try and cut tv/phone earlier might help and sometimes it's got nothing to do with those things folks who aren't neurotypical often have trouble with sleep or feel sleepy at later times than the average, not implying but it's something I learned myself that really resonated.
Lastly a tip from this insomniac...don't stay in bed and toss and turn for hours, get up, get a glass of water. Go sit on the coach and read a book or whatever, look out window, worse case put on a boring tv show until you feel sleepy again. Resetting yourself for sleep is a lot more helpful than getting anxious in bed about not sleeping.