I think reiterating that point about sleeping with a guy too early is needed here. Basically when you have sex with a guy so early he isn't going to see you as relationship material - why should he? He's got everything he wants from you so he has no motivation to push for a deeper relationship.
I know it seems such a cliché to hold back from sex, and I know how hard it is when you feel that intense spark. But you really need to see this as a long term investment. Hold off from the sexual side and focus on the emotional side, it will only work in your favour.
By doing this you allow yourself and him time to learn about each other, it gives you both a chance to fall in love.
As for the texting - pull back. Focus on your life, focus on other men/dates and stop making him your priority as you definitely are not his. Perhaps in a couple weeks send him a "hey, how are you?" message, but stop initiating - you're giving him all the power by doing so and undermining yourself in the process.
Also remember - if a guy is interested in you aside from just sex, he will move mountains to see you, too message you or to phone you, if he's sporadic with his contact, chances are he's not that into you.