This situation reminds me of the Pylon (from "Chain") lyric:
"What am I supposed to do?
What am I supposed to do?
What am I supposed to do?...There is no solution."
While it may be false that there is "no solution" to your conundrum, it is indeed true that the self-evident solutions are in fact highly imperfect, personal and painful.
Note: You have already stated that you are far from gay, but allow me to include the gay scenario as well for the sake of comphrehensiveness.
Three possible options:
(1) You find a woman who will "tolerate" your condition. Like someone else already said, this is not an impossible feat and is somewhat akin to a female with small breasts finding a significant other, only in the case of the male suitor, it is even more difficult because not just any prospective girlfriend you meet can look at you and plainly tell you have a 4 1/2 inch erect penis as soon as she sees you (as is not the case with smaller bust sized women, whose breast size is immediately recognizable to anyone and everyone who lays eyes on them) and because the penis, moreso than the female mammary glands, is more directly involved in human sexual gratification and sexual reproduction.
This fact makes for awkward dating scenarios because you will constantly be harried by the question, "When should I tell her?" If one out of twenty dates is not bothered by your very personal situation, then you will be forced to endure myriad, time-consumming, painful rejections before finding even the first good prospective match. Other men in your situation may choose to avoid dating altogether because being merely "tolerated" by a life partner is not enough which leads to (2).
(2) You remain stoically alone, while everyone around you gossips, at times maliciously, or merely wonders to themselves what is in fact "wrong" with you, a man of 27 years of age, as if being born modestly endowed is somehow a heinous crime against the human race.
Will they say that you are asexual? What about diseased? Deformed? Gay? Perveted? Impotent? Unstable? Insane?...you get the idea.
The list is endless, predictable and horrid and is only made worse by the answer that the only thing "wrong" with you is the way you are made: a condition which neither you nor anyone else can realistically change in this lifetime. Sure, there are surgergies, penis pumps, implants and pills, but their safety and efficacy is questionable at best.
(3) The Gay Card.
You look for a "top" man. For whatever reason, however, most gay men are even more obsessed with big dicked guys than the average nymphomaniac and much more so than the average, sweet girl next door.
However, I have been told and have seen online, that there are some gay men who want a smaller dicked man because they either want to have the bigger dick in the bedroom at all times or because they have a particular fetish for small dicks. The former types tend to be abusive control freaks, while the latter category borders on the freakish, although I have personally never met (to my knowledge) either type in person.
In short, there are no easy answers to your very private yet very public dilemma. However, until you can accept your body as yourself, then you have let the small dick haters win.