wilrob, if you do not have the marriage certificate, get a copy of it. Then tell us the name and occupation of Jane Guthrie's father. Without that, you are not going to get any further.
FreeCEN lists in the 1841 census a family at 6 Heriot Bridge, Grassmarket that includes John Guthrie, 54, damask maker, wife Christian and children including Jane, 21. There is also a Thomas Thomson, aged 56. This is the family of John Guthrie and Christian Thomson, so you can eliminate that Jane Guthrie as a candidate for your Jane Guthrie.
What you cannot do, however, is assume that the other Jane Guthrie baptised in Edinburgh in 1821, daughter of John Guthrie and Jean Laidlaw, is yours. There could be others whose baptisms were not recorded.
If Jane's marriage certificate tells you that her father's name was John, you are then one stop closer. If his occupation as stated on the marriage certificate matches his occupation (if any is given) on the baptism record of Jane Guthrie, daughter of John Guthrie and Jean Laidlaw, then you would, I think, be justified in thinking she is the right one.
