Frame sizing help needed please

morning folks. so i bought an off the peg lemond fillmore, a size 53. built it last night and have this sinking sneaking feeling its too small for me. i've ridden mountain bikes for so many years (even my road fixed and touring bikes are built on 29er mountain bike frames), i got a bit weirded out by the sizing of road frames. basically im 5'10" and now im thinking i should have got a 55 or even a 56? i like frames with low standover height but dont want to be bunched up all uncomfortable when ii change the drops for risers. i think i was thinking about the lemond being compact frame but its not so maybe thats where i went wrong. also, i cant return it as i didnt get it from a shop, ya dig, and i dont really wanna be riding it about if i need to sell it on as id rather keep it mint,(welll mostly, i already put a small scratch in the top tube). so heres the crack, can people my height tell me what frame size they ride and maybe even a top tube length so i can do a little research properly and make an informed decision please... thanks everyone. oh and on a side note, its horrible riding a bike with a freewheel after fixed eh, makes you feel like your legs dont work properly.

** Determine Your Proper Frame Size **

  To determine your proper frame size, you'll first need to get an accurate inseam measurement . Stand with your back against a wall, your bare feet 6" apart on a hard floor, looking straight ahead. Place a book or carpenter's square between your legs with one edge against the wall, and pull it up firmly into your crotch, simulating the pressure of your saddle while riding. Have a helper measure from the top edge of the book to the floor, in centimeters. (You can convert inches to centimeters by multiplying inches by 2.54.) Repeat two or three times, for consistency, and average the results to get your inseam length. 
         **         Frame Size     **

  Frame size refers to the length of the frame's seat tube. Pro frames are measured along the seat tube in one of two ways, center-to-top (C-T) or center-to-center (C-C). C-T measures the distance from the center of the bottom bracket to the top of the top tube or seat lug (See image bellow). C-C measures from the center of the bottom bracket to the center of the top tube. Since C-T measures to a point higher on the frame, a frame measuring 55cm C-T would also measure roughly 53.5-54cm C-C, a difference of 1-1.5cm. 
  To size your C-T road frame, we use a guideline of .67 x inseam length. For example, if you have an 85cm inseam, your C-T frame size would be .67 x 85cm, or 57cm. 
  LeMond's formula, from his former coach, Cyrille Guimard, establishes C-C size by the formula .65 x inseam length, which yields virtually the same frame size when you add the 1-1.5cm difference between C-C and C-T. 
  Larger riders (6'0" and up) may find that this formula puts them on a too small, and uncomfortable, road frame. A taller cyclist who wants a more comfortable frame may be better off selecting a frame 27-28cm less than inseam length, C-T. 
  For a mountain bike, we start by recommending a frame in the range of 10-12cm smaller than you take in a road frame. For example, if you ride a 55cm C-T road frame, look for a 43-45cm (17-18") C-T mountain frame. 

http://www.coloradocyclist.com/bikefit#framedimensions

i think if you like small bikes a 53 will be OK, better to be small than big.

i think if you like small bikes a 53 will be OK, better to be small than big.

Definitely agree with this having spend a whole heap of cash at the oesteopaths fixing back and elbow problems caused by riding a bike that was too big.

im about your height (or inch taller?). for a road bike, i normally take a frame that's got 550mm top tube length then put on a 100mm stem. from filmore's geo, 53cm will do...i'd put a slightly longer stem on.

if it helps, on an xc mtb i normally take 18in. mtb frames are longer on the top tube.

dont get the standover height thing tho. on the road, you're more likely to go over the bars than your jewels hitting the toptube

I'm the same height as both of you and ride a 56 which I find to be perfect. I also used to ride a 53, and found it to be too small, but only because of the top tube length.
also use this calculator:
http://www2.bsn.de/Cycling/ergobike.html

alright nice one folks. reckon i've got some measuring and thinking to do. thanks for the help and suggestions.