Okay firstly mate, i have previously been rubbish on previous FIFAs defensively, your current experience sounds like my normal one too, however i have been playing really well of late and i have been playing 442 too. It's all about your two centre mids
Keep your fullbacks on stay back, keep your defensive DM on stay back, aggressive interceptions and cover center. Keep your other centre mid on default but add aggressive interceptions and cover centre too.
Secondly, DO NOT select your centre backs unless the striker has received the ball and is running past you in the penalty box. Other than that, control your CDM (mine is fabinho and partnered with Thiago who is on Shadow chem). And just select between the two CMs to press the opposition. Let them pass it around you, if they pass to the winger then select the full back and just show them down to the corner flag until they pass back to midfield. Eventually they will make a mistake.
Thirdly, Sprint Jockey with your CDM or CM into the tackle, never press circle unless its desperate. Just be calm, shield your centre backs and keep flicking between your CMs to press the attackers. You can occasionally use R1 to call a second teammate to press too but this pulls your CBs out of position.
Also, in your position, i would personally avoid pressing. It will pull your defence out even more and likely leave you exposed like you are. When the attackers are running at your defence, just select your cdm and try and get him back. The attackers will continue to pass it to each other in the hope you will move your centre back. Just play calmer.
Lastly, always assume the attacker wants to cut back for an easy pass. So always show them to the byline, don't commit and think you can nick a tackle with circle, just jockey or sprint jockey until you get near them and can bump into them. Once you get to a stage you are getting close enough to make challenges on them consistently then you are getting better at defending and can start gambling with a circle tackle when you get near enough with the jockey.