Does this mean someone blocked my number on iphone?

Usually when sending an iMessage, it will show up "delivered", then if it doesn't go thru it will turn Green as it was sent as a SMS. But for the past 3 days every text I send DOESN't say delivered, it says nothing, and STAYS blue. So strange. As I tried calling and it rings the average amount of times then goes to VM so I imagine IIm not blocked but can't figure out the text thing. It's staying Blue and doesn't say delivered. IIm not getting a response on the text obviously.

No, you can't tell whether you are blocked or not.

It may be possible, in case you need to have a good security app try Leo Privacy Guard, it's the best one.