Well I pray that you learn to speak in tongues one day. It is very edifying. A few pointers to get you in the right direction is to remember, when you speak in tongues you are the one doing the speaking. God is forming the words that come out but you are the one pushing the air out of your mouth. Its a big myth in the church that god or the holy spirit just takes control of you and you start speaking uncontrollably. It just isn't the case. Another pointer is start small with a few syllables at a time. For practice say something like "ah" "le" "to" "so". Like someone learning a new language you have to start small and before you know it you are fluent in it. Here is also a video that will help you speak in tongues.
Good luck. Once you get the hang of it you may have doubts like wow am I really doing it. But overtime those doubts fade the more you do it. And you become an expert at it.
I apologize for seeming blunt, but this entire post appears opposite of scripture. 1 Corinthians 12 very specifically states that tongues are a gift given to certain individuals and not all. He also considers it the least of the possible gifts, and says you should be eager to receive the greater gifts. But nonetheless, he states multiple times in Chapter 12 alone that there are separate gifts for separate people. "There are different gifts but the same spirit." (4-11) The Spirit is "distributing as he decides to each person." "If they were all the same member, where would the body be?" (12-26) "Not all speak in tongues, do they?" (28-31)
There is literally an entire chapter that spells out that tongues are not learned and are a gift of the Spirit only given to select people. You are correct that Paul told the church he was speaking with to remain silent if no one was present to translate. However, it never states only the person who speaks it should interpret. It says someone should interpret, and Acts 2 even details those completely outside interpreting. In fact, it gives one of the best examples of tongues being translated (as 1 corinthians 14 states, thus tongues are a sign not for believers, but for unbelievers.)
In Acts 2, the crowd that gathers is able to interpret the Galileans' speech, as they were hearing their own languages. They heard them speaking of God's great deeds in their own tongues. This scripture backs up the only example I personally know of interpreted tongues of that nature, where a Lebanese unbeliever heard a believer speaking in tongues and asked her "You speak Arabic?" They replied, "no, not at all. What are you talking about?" And the unbeliever then translated everything the woman had said in tongues - that she had been speaking about God's great deeds in fluent Arabic and praising him.
Now, I'm no one to say I completely understand the gift of tongues or its purpose at every turn. But we do know Paul was giving these instructions to a church he considered "carnal." And we do know that in Acts, the tongues were very clearly standard foreign languages spoken by others, who were able to translate them and realize God's glory. (Though some just said they're drunk and shouting nonsense, basically.) And we know that without translation, they are to be kept private. Further, we know that it is not learned, but a gift of the Spirit not everyone may receive; and it is also the least of the gifts we should wish to receive.
None of this is my opinion. This is simply what the Bible states, no matter what version you prefer to read. So if you've never received the gift of tongues, it's nothing to "try harder for or practice." That gift simply hasn't been given to you, and you should still long for the greater gifts God may have in store for you. The woman in the story I mentioned - it happened at that specific time, for God's glory. She was given the gift of tongues for that unbeliever to hear and know there is a God beyond our comprehension.
