There is absolutely no shame in choosing a civil ceremony at this time in your relationship. You two are committed to each other and have been together for three years I believe you said. Every relationship is going to have their struggles and you guys know about yours. Please don't compare yourself to couples who have been together 6 months and married in the temple right away. Their struggles and temptations might not be the same as yours, not to mention the fact that of course it's going to be easier to abstain from sex when being together a much shorter time. And a couple who looks picture perfect from the outside and who is sealed, might be dealing with issues you can't see - infedility, porn, lack of intimacy in marriage, communication issues, etc. You have been together long enough to know you are a strong couple and that you can work towards your goal of being sealed in the temple for time and eternity together. And think how much you will appreciate that when the time comes.
I was married civilly and was recently sealed to my sweet husband. This is my second marriage, and the first time I got married I was 19, dated the guy for 6months and was sealed in the temple. Sure, I had the right plan in getting sealed right away but I can tell you that with my current marriage, after waiting and working together on being sealed, I appreciate it SO much more and have such a strong testimony of its power.
Sure, I hear comments sometimes from people at church who seem to think civil marriages are a sad affair and how it's so tragic they say "till death do us part". Of course I didn't like that part of my civil marriage, hearing those words. BUT luckily our wonderful bishop expounded on how much we had to look forward to as a couple and getting sealed, that we just focused on what we had to look forward to, not the fact we were "settling". Because we weren't settling, we were just using that experience as a stepping stone to our future goal.