You can't avoid taxes on an EE bond; it accumulates tax deferred, not tax free. You do get to pick the year you sell it. However, if it has already matured, you're losing any future interest.
IRA contribution limits apply to the sum total of multiple non-tax retirement accounts & depending on if they are funded pre or post tax. Multiple retirement accounts are OK if there's a reason for each of them, i.e. 401K (payroll deduction, reduces MAGI up to defined limits, & taxed as ordinary income when redeemed), traditional IRA (reduces MAGI up to defined limits or just defers taxes on the interest if not, & taxed as ordinary income when redeemed), & Roth IRA and/or Roth 401K (post-tax contribution & tax-free redemption). You could have a tIRA created from a rollover from a 401K from an employer you no longer work for. There are also SEP-IRA & SimpleIRA accounts for the self-employed & small business.