THIS POST HERE. Is one of the reasons I have been a member of this forum for so long. A WEALTH of valuable information always comes to the surface. Thanks is not enough.
OP, Farida is an attorney and she knows what she is talking about. Besides making your engagement and wedding plans, be SURE to take your immigration requirements into consideration first and foremost. It sounds like it will dictate how all of your other plans for the wedding need to proceed.
I have to disclaim, I am not licensed in any state (yet, I hope) so I am not a lawyer. I graduated law school and I have worked in immigration under the supervision of licensed attorneys and T.A'ed an immigration law course. So all this is my opinion, not a legal one because I cannot give legal advice especially without knowing OPs situation. Which is why my advice is to get a lawyer. I have seen things, which I cannot divulge because privilege/ethics forbids me, so I can only comment generally.
Immigration law is hopelessly idiosyncratic.
For example, if a person who entered the states on a visitor's visa (B1) with the intent just to visit or F-1 as a student, and for some reason overstays, and then later meets someone, gets married and then decides to move permanently, if certain requirements are met the person's overstay will be forgiven (waived) as an "immediate relative" a.k.a spouse, and the person entered the country legally and will be allowed to eventually get a green card and then citizenship later.
However, if a person enters the states on the visa waiver program as a visitor with the intent to visit and then overstays, and then decides to move permanently and has married someone, the person cannot get a green card! Having overstayed the VWP, the person now faces a ban. If the person leaves the country, the bans run from 3, 5, 10, 20 to lifetime bans! So the person can risk going to USCIS and hope they look the other way, or go to USCIS and risk being deported with a ban. The person is not eligible for a waiver!
People don't expect that outcome. The two situations are almost exactly the same. In fact you would think they would have more love for countries we have the Visa Waiver program deal with. The exact opposite for the VWP.
Also, once you get married your spouse has to file WITH you to allow you to get a permanent green card. I see cases where the spouse refuses to file with the person, runs off to another country or even dies. It is such a headache. Yet, if you are married for 3 years (I don't recall) before you move to the states, all you do is file for the green card and bam. No conditional green card for 3 years blah blah. But even coming in already married IMO is easier than coming in as a fiancee.
Also, depending on where you are from (citizenship) USCIS can really harass couples. For example if you are Vietnamese, Filipino, Indian, Mexican etc they automatically work off of the assumption that the marriage is fraudulent. Couples that date separately (not in the same area, long-distance) or overseas or even domestic are encouraged by lawyers to keep a record of their romance. Photos, e-mails, letters, meeting the family etc. Anything to support a bona fide marriage.
Assuming OP is from Germany and is a German citizen then they don't hassle those folk as much. But still keep a paper trail. Some Immigration Service Officers (ISOs) can be real ___________ .