Twitter embedded timelines receive a refresh in Jetpack 4.1. If you prefer using Jetpack you can switch to having the plugin manage embeds once the next plugin update ships.
You may set the Tweet limit by adding data-tweet-limit="4" to your <a> element. Replace 4 with the number of Tweets you would like to display.
<a class="twitter-timeline" href="https://twitter.com/Travel_Acoustic" data-tweet-limit="4">Tweets by Travel_Acoustic</a> <script async src="//platform.twitter.com/widgets.js" charset="utf-8"></script>