Mr. Knowitall is absolutely correct that you need to retain an experienced immigration lawyer in your area. If those are the only 2 trips you have had in the past 5 years, then you have only been absent from the US for one year and 1 week. I say only because one of the eligibility requirements for US naturalization is that you are physically present in the US for half of 5 years, which is approximately 30 months. It appears you have met that requirement.
Where it gets tricky for you is that on the N-400 form, you will have to state that yes, you have been out of the US for over 6 months. As Mr. Knowitall correctly states, there is a presumption that you have abandoned your green card, but this presumption can be overcome by you presenting documents to show that you still maintained significant ties to the US.
If you contact an immigration lawyer in your area, he or she can tell you what types of evidence the USCIS office in your area will want for you to overcome the presumption. Usually filing US income taxes during that time, having proof of legal residence (i.e. lease, mortgage, etc) can be helpful, and proof of your husband's studies abroad will help explain your circumstances.
If you cannot afford an attorney, then at least go in for a consultation to get information as to how USCIS in your area would treat a case like yours and to get a list of documents you can collect to provide to USCIS. I wish you much luck.

