Regarding speaking in tongues, the Bible never tells us that we must speak in tongues. A good passage is 1 Cor 12:27-31:

“Now you are the body of Christ, and each one of you is a part of it. 28And in the church God has appointed first of all apostles, second prophets, third teachers, then workers of miracles, also those having gifts of healing, those able to help others, those with gifts of administration, and those speaking in different kinds of tongues. 29Are all apostles? Are all prophets? Are all teachers? Do all work miracles? 30Do all have gifts of healing? Do all speak in tongues[a]? Do all interpret? 31But eagerly desire the greater gifts”.

The obvious answer to his rhetorical question (in bold) “No, of course they don’t!”. This idea is picked up earlier in 1 Cor 12:7-11, where different gifts are given to different people as the Spirit determines. This is a really clear answer from the Bible (yay!), the Bible doesn’t tell us that we must speak in tongues.

Which brings us to the second part of your question about whether Christians who speak in tongues are some how superior to those who don’t, or whether we’re missing something. Back in the first passage the last verse says that we are to “eagerly desire the greater gifts” (V31). But V28 tells us that they are more like the gifts of apostleship (which you and I aren’t!), prophecy, teaching etc… In fact, tongues are last on the list! The gift of administration is even above tongues in this ordered list. Sometimes it’s easy to over-emphasise tongues because they look impressive, when really God values other things more highly.

Don’t get me wrong, tongues are still a gift from God and still good, but the exact problem the Christians in Corinth had was that they played a game of one-up-manship based on who had the better gift, and who followed the ‘better’ Apostle - and that’s why Paul hammers them in 3:1 as “mere infants in Christ”. Don’t let whether you speak in tongues or not shake your confidence in Christ!

Finally, I think it’d be really good to be encouraged by what Christianity is all about. Have a read of this:

“Praise be to the God and Father of our Lord Jesus Christ, who has blessed us in the heavenly realms with every spiritual blessing in CHRIST”. (Eph 1:3)

If you have Christ, you have it all!! That’s worth remembering I think.