Too short a 2nd phase is likely the result of having too large of a hop (1st phase) or wanting a huge jump. One goal in the TJ that I like to see is conservation of momentum and subconsciously your brain and body understand this as well. The shorter step phase is a result of trying to maintain velocity most likely a result of the hop, but it can also be done in preparation for a huge jump phase. Usually error identification and correction is done by back tracking and I think you will find that your step phase distance is a symptom of something else. A controlled approach with a controlled hop will likely yield greater step and jump phases if you are at roughly the same velocity with a shorter initial hop, but your jump distances likely be farther. I think you’ll find this relates back some of the posture arguments as too long of a hop probably has some excessive forward rotation involved which would lead to longer ground contact times on the step that result more in braking than forward and vertical propulsion. The TJ should have a nice rhythm to it as well and a more controlled hop phase will likely yield huge dividends once you work through the timing involved to produce a better rhythm. If you are a high school athlete and are not a senior, I wouldn’t change a thing right now and would look towards next year beginning this summer and fall.
One thing I would like to point out for you to do is probably more elastic, eccentric, and reactionary strength work (ie.. plyos) to build more specific event strength outside of the context of the event itself and obviously doing more core work if you are deficient in these areas. For these you don’t need a weight room or a facility to jump at and during the summer and fall they would provide a great stimulus while you would only need to practice actually jumping 1x a week to get a new feel for a rhythm.