Appraisal came in way under for FHA buyers

[Tom Del]

I am selling my house for $299,000 as a FSBO and the buyers are pre-approved for an FHA loan. However their appraisal just came back for $266,000 which I believe is incredibly low for the home, the neighborhood, the market, and the lack of inventory on the market. I've requested a copy of the appraisal and comps, but haven't yet received it. The buyers realtor pulled her own comps and I did the following analysis. What are your thoughts?

Comp	My Home	Comp	My Home	Comp	My Home	Comp	My Home As Appraised ($266k - $118 sqft)	My Home As Listed ($299k - $133 sqft)	Comp	My Home	My Home vs Comp	Comp	My Home	My Home	Comp	Comp
Address	Bed	Bed	Bath	Bath	Sqft	Sqft	$ Per Sqft	Sqft Cost Comparison	$ Per Sqft	Lot Size	Lot Size	Lot Size	Year Built	Year Built	Yrs Newer	Price	Date Sold
Comp 1	4	4	3	3	1926	2236	$ 134.48	-12%	-1%	8398	10454	24%	1995	1999	4	$ 259,000.00	10/19/2017
Comp 2	3	4	3	3	2446	2236	$ 108.30	9%	23%	10236	10454	2%	1963	1999	36	$ 264,900.00	12/11/2017
Comp 3	4	4	3	3	1345	2236	$ 200.74	-41%	-34%	10138	10454	3%	1980	1999	19	$ 270,000.00	9/26/2017
Comp 4	4	4	3	3	1249	2236	$ 255.22	-54%	-48%	8455	10454	24%	1996	1999	3	$ 318,771.00	12/12/2017
Comp 5	4	4	3	3	2486	2236	$ 116.65	1%	14%	16117	10454	-35%	1975	1999	24	$ 290,000.00	11/16/2017
Comp 6	4	4	3	3	2276	2236	$ 127.33	-7%	4%	10890	10454	-4%	1978	1999	21	$ 289,800.00	2/15/2018
Comp 7	4	4	3	3	2695	2236	$ 107.98	9%	23%	28185	10454	-63%	1979	1999	20	$ 291,000.00	11/13/2017
Comp 8	4	4	3	3	1134	2236	$ 264.55	-55%	-50%	10018	10454	4%	1999	1999	0	$ 300,000.00	9/29/2017
Comp 9	4	4	3	3	2557	2236	$ 123.15	-4%	8%	13068	10454	-20%	1989	1999	10	$ 314,900.00
Comp 10	4	4	2.75	3	2266	2236	$ 135.92	-13%	-2%	8712	10454	20%	1971	1999	28	$ 308,000.00	11/3/2017
							% comparison on a cost per sqft basis. Comparing the comp vs the $266k appraised value. Negative values denote 3403 being under valued per sqft compared to comp	% comparison on a cost per sqft basis. Comparing the comp vs the $299k sale value. Negative values denote 3403 being under valued per sqft compared to comp			Lost size comparison. Positive numbers indicate % 3403 is larger than comp