Even though it can be done, and you've mentioned someone else you dated would text you more frequently, most people do not want to be contacted that much....especially working people.

It can be very distracting when someone texts that amount when you're trying to work. Plus, the other person can feel smothered or have that feeling that you don't have interests outside of them since you're spending all your time and energy contacting them.
No offense, but it sounds like you are overly dependent on constant contact, otherwise, you feel like you do not measure up or have doubts in someone's interest when really you are pushing them away further. There are ways you can work on not being dependent on others for your own happiness. If you can't go to therapy, then you may want to consider self-help through books, videos,etc.