I have a Clematis that is 3 years old, it only has one vine

give us a clue! When does it flower and what colour is it, the when being the most important question to answer?

Purple and it is about to flower anytime soon

purple will flower soon

Okay, that means it's a Prune group 3 Jackmanii variety. Leave it as it is this year - when it gets to February, go out and chop that stem down to 2/3 leaf buds from the base (probably 6 - 8 inches up from soil). Not only will that stem regrow, this pruning should encourage more shoots to be produced.

Do this every year at the same time.

Though actually, it occurs to me belatedly, has it flowered once already this year, earliesh, say May time? This group produce two lots of flowers, early and then again any time now.
If it has flowered once already and this is the second lot, still do what I said in February, but don't do it every year. You will lose the early flowers, but you will still get the later ones.

This will be the first time it will flower and I did cut it back but not in February. I live in Saskatchewan Canada and we had a late spring so I cut it back April 30th timeframe, I cut it back 2 - 3 inches from the ground.

Hmm, well, is it in the ground or in a pot? I'm assuming its in the ground because it'd probably die in a pot in your very cold winters. Does it get enough water and are you feeding it during the growing season. When you've cut it down next year, and growth begins, try feeding it with a nitrogenous fertiliser (here its called Growmore or Miracle Gro general purpose, no idea what you've got there). If ever you put in another clematis, remember to dig a deep and wide hole, 10 inches from the wall or fence or whatever, and lay the rootball in at an angle, not quite sideways on, but more or less. This encourages shoots to come up off the rootball, heading for the light. Good luck.

Yes it is in the ground. It gets lots of water but I havent fertilized it, I will have to try the Miracle Grow. Thanks for you information

Apped, you can buy a specific clematis granular fertilizer. I can't remember the brand name. It was fertilizer for clematis and vines. Have a look at your local garden centre. For a spring feed it should be a high first number which indicates the nitrogen percentage.
Miracle Grow is good. Over here, the miracle grow all purpose, water soluable is a 24-8-16. That is a nice high nitrogen level. However, don't use the Ultra Bloom as this is a high middle number....15-30-15 and will promote flowers but not so much growth.