2 yards would only give you a 6 foot long quilt. If you sew a flat footbox that quilt would only come up to your shoulders ... not quite long enough. I'm 5'10" and I tried this once upon a time ..... didn't work for me.
2.5 yards is the minimum IMO.
I ordered 5 yards of the momentum ripstop and 4 yards of 2.5 oz basis weight XP, then folded the XP at the base and doubled up the thickness up to mid stomach level. This gave me 2.5 oz on the top and 5 oz on the bottom. I then wear my high loft pullover to bed. I've had this down to the mid 20's this way and was comfy.
I used ripstop for the inside and the outside because if I tear/burn one side I wanted to be able to turn the quilt inside out and still have a unbroken momentum top to face the weather. Cost with Shipping was around $110 for the materials.
Myself, I would order 3 yards of the 5oz basis weight so I didn't have to mess with basting ... and then use the extra for other projects, but you could get away with 2 yards and some basting from the side pieces .... you'll have to quilt the quilt with yarn loops or something similar to stabilize the basted pieces, however, so if you're going to baste, there's no need to use momentum for the inside that you're going to yarn quilt the insulation to, so just use regular DWR nylon at less than half the price. The weight penalty is about a half ounce.
In fact .... your really on a budget, you may want to consider using standard DWR nylon on both sides and plan on using a Bivy. I really like working with the Momentum, however, for a ounce more you could save about $40.
Something to consider
A drawstring along the top is nice to "shape" the quilt to your shoulders.
One last note ... I went back to a quilt because I'm clostrophobic in a bag, and I went to synthetics because I'm that 100th guy that, for some screwed up reason, keeps getting his down bag damp or wet at least twice a year. I had a really hard time starting a fire on my Summer trip to the Pecos Wilderness and with a wet me and a damp bag I was facing a really bad night, wet windy, with temps at around freezing. Luckily I was able to sacrifice my cotton sleep shirt and with that and a bit of vasaline, I managed to get wood that had sat out in two weeks of rain to dry out enough to get a fire going.
My 20 degree, 18 oz, oversize synth quilt is here to stay.